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CCNA Mobile Devices Troubleshooting Questions

30 questions · Mobile Devices Troubleshooting topic · All types, answers revealed

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1
MCQeasy

A user reports that their iPhone 12 will not turn on after being left in a hot car for several hours. The device feels warm, and pressing the power button does nothing. What is the most likely cause of the device not powering on?

A.The battery has expanded due to heat and disconnected from the logic board
B.The device's logic board has been permanently damaged by heat
C.The device entered a thermal shutdown state to protect internal components
D.The power button is stuck due to heat expansion
AnswerC

iPhones have thermal sensors that trigger a shutdown when internal temperatures exceed safe limits. Once cooled, the device should power on normally.

Why this answer

Excessive heat can trigger thermal protection circuits in modern smartphones, causing them to shut down and refuse to power on until they cool down. This is a safety feature to prevent battery or component damage. The correct answer identifies thermal shutdown as the cause.

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2
MCQmedium

A user complains that their Android tablet's touchscreen is unresponsive in a vertical strip down the middle of the screen, but the rest of the screen works fine. They have restarted the device and removed the screen protector. What is the most likely cause?

A.A software glitch in the touchscreen driver.
B.The screen protector is causing interference.
C.The LCD panel is failing.
D.The digitizer is damaged.
AnswerD

The digitizer is the touch-sensitive layer. Physical damage (e.g., from a drop or pressure) can create a dead zone in a specific area. This matches the symptom exactly.

Why this answer

A vertical strip of unresponsive touch input is a classic sign of a damaged digitizer. The digitizer is the layer that detects touch, and it can be physically damaged (cracked internally) even if the glass appears intact. Software issues typically cause full unresponsiveness or erratic behavior, not a precise dead zone.

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3
MCQhard

A technician is troubleshooting a Samsung Galaxy tablet that will not rotate the screen when the device is turned sideways. Auto-rotate is enabled in the settings, and the screen rotates correctly in safe mode. What is the most likely cause?

A.The accelerometer is faulty.
B.A third-party app is preventing rotation.
C.The auto-rotate setting is only enabled for certain apps.
D.The tablet's gyroscope needs calibration.
AnswerB

Some apps, especially games or video players, can lock the screen orientation. When running in the background, they can override the system setting. Safe mode confirms this by disabling all third-party apps.

Why this answer

Since auto-rotate works in safe mode, the hardware (accelerometer) is functional. The issue is caused by a third-party app or a system setting that is interfering with rotation. Safe mode disables third-party apps, so the problem is likely a recently installed app that is locking the orientation or a setting within an app that overrides system rotation.

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4
MCQmedium

A technician is setting up a new Android tablet for a field sales representative. The tablet needs to connect to the internet via a cellular data plan. The technician inserts a nano-SIM card from the company's carrier, but the tablet shows 'No SIM card' in the status bar. The SIM card works in another tablet. What is the most likely cause?

A.The tablet's cellular radio is disabled in the settings.
B.The SIM card is not compatible with the tablet's LTE bands.
C.The SIM card is not fully inserted or is inserted incorrectly.
D.The tablet requires a software update to enable cellular functionality.
AnswerC

This is the most common cause of 'No SIM' on a new device. The SIM tray may not be pushed in all the way, or the SIM is upside down. Re-seating the SIM correctly is the first step.

Why this answer

If the SIM card works in another device, the issue is with the tablet itself. The most common cause is that the SIM card is not fully seated or is inserted incorrectly. Some tablets use a tray that requires the SIM to be oriented a specific way.

A less common cause is a faulty SIM slot, but that should be checked after verifying correct insertion.

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5
MCQmedium

A user reports that their iPhone 13 will not charge when plugged into the charging port. The user has tried different cables and power adapters, but the phone still does not charge. The phone's screen and buttons work normally. Which of the following is the most likely cause?

A.The battery is completely dead and needs replacement
B.The Lightning port is clogged with debris
C.The operating system is corrupted
D.The phone's wireless charging coil is damaged
AnswerB

Debris in the port can prevent the connector from making full contact, stopping charging even with a working cable and adapter.

Why this answer

Since the user has already ruled out the cable and adapter, the issue is likely with the phone itself. A common problem is debris or lint compacted in the Lightning port, preventing a proper connection. Cleaning the port carefully can often resolve this.

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6
MCQhard

A user reports that their smartphone's screen is flickering and has vertical lines. The phone has not been dropped or exposed to water. Which of the following is the most likely cause of this issue?

A.A software glitch caused by a recent app update
B.The battery is swelling and pressing against the display
C.The display cable is loose or damaged
D.The phone's processor is overheating
AnswerC

A loose or damaged display cable can cause intermittent or permanent display artifacts like flickering and vertical lines.

Why this answer

Screen flickering and vertical lines are classic symptoms of a failing display or a loose internal display cable. Since there was no physical trauma, a loose connection or a manufacturing defect in the display assembly is the most probable cause.

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7
MCQhard

A technician is troubleshooting a laptop that powers on but displays a black screen with no boot activity. The technician hears the fan spinning and sees the power LED is on. Which of the following steps should the technician perform next to isolate the issue?

A.Reseat the RAM modules
B.Replace the LCD panel
C.Connect an external monitor
D.Reinstall the operating system
AnswerC

Connecting an external monitor tests whether the laptop is outputting video; if it works, the internal display or cable is the problem.

Why this answer

A black screen with power but no boot suggests a hardware issue, often with the display or memory. Connecting an external monitor can quickly determine if the problem is with the laptop's LCD panel or the video output. If the external monitor works, the internal display or its cable is likely faulty.

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8
MCQeasy

A user complains that their laptop's Wi-Fi connection is extremely slow and keeps dropping, but other devices on the same network work fine. The laptop is an older model running Windows 10. Which of the following should the technician try first?

A.Replace the laptop's Wi-Fi card
B.Update the Wi-Fi driver
C.Disable the firewall
D.Reset the router
AnswerB

Updating the driver can fix bugs or compatibility issues that cause slow speeds and disconnections.

Why this answer

An outdated or corrupted Wi-Fi driver is a common cause of connectivity issues on older laptops. Updating the driver is a software-level fix that is quick and non-invasive, and it often resolves intermittent connectivity problems.

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9
MCQeasy

A user complains that their laptop's touchpad cursor jumps erratically while typing. They have cleaned the touchpad surface, but the issue persists. Which configuration change should you try first?

A.Increase the touchpad sensitivity in the operating system settings.
B.Update the touchpad driver from the manufacturer's website.
C.Enable the 'Ignore accidental touches' or 'PalmCheck' feature in the touchpad settings.
D.Disable the touchpad entirely and use an external mouse.
AnswerC

This feature is designed specifically to suppress touchpad input when the keyboard is being used, preventing the exact symptom described. It is the quickest and most effective first step.

Why this answer

Erratic cursor movement while typing is a classic sign of palm rejection not working correctly. The most common fix is to enable the 'disable touchpad while typing' feature in the touchpad settings. This prevents accidental input from the user's palms during typing.

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10
MCQeasy

A customer brings in a laptop that will not charge. The technician checks the AC adapter with a multimeter and gets 19V output. When the adapter is plugged into the laptop, the charging LED does not illuminate. What should the technician check next?

A.Replace the laptop's battery
B.Test the DC jack for continuity
C.Update the laptop's BIOS
D.Replace the AC adapter with a universal one
AnswerB

A broken DC jack or loose connection can interrupt power delivery even if the adapter is good. Checking continuity verifies the path from jack to motherboard.

Why this answer

Since the AC adapter is outputting correct voltage, the issue is likely in the power delivery path. The DC jack is a common failure point due to mechanical stress or broken solder joints. Testing continuity at the jack is a logical next step.

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11
MCQmedium

A technician is troubleshooting a laptop that has a blinking battery light and will not power on, even when plugged into AC power. The technician has already verified the AC adapter is working on another laptop. Which component is most likely faulty?

A.The CPU
B.The RAM
C.The battery
D.The hard drive
AnswerC

A failed or deeply discharged battery can cause a blinking light and prevent the laptop from powering on, even with AC power connected.

Why this answer

A blinking battery light often indicates a battery or charging circuit error. Since the AC adapter is known to be good, the issue is likely with the laptop's internal battery, the DC jack, or the charging circuit on the motherboard. The battery is the most common failure point.

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12
MCQmedium

A technician is configuring a new Android tablet for a warehouse employee. The employee will use the tablet to scan barcodes and access a web-based inventory system. The tablet needs to stay connected to the Wi-Fi network even when the screen is off to receive updates. Which setting should the technician configure?

A.Set the screen timeout to 30 minutes
B.Enable 'Keep Wi-Fi on during sleep' and set it to 'Always'
C.Disable Bluetooth
D.Install a third-party app to keep the screen on
AnswerB

This setting ensures the Wi-Fi radio remains active even when the device enters sleep mode, allowing continuous connectivity.

Why this answer

Android devices have a power-saving feature that disconnects Wi-Fi when the screen is off to save battery. To ensure the tablet stays connected, the technician must change the 'Keep Wi-Fi on during sleep' setting to 'Always'.

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13
MCQeasy

A customer reports that their Android smartphone's screen remains black when they press the power button, but the device vibrates when receiving calls. They have already tried a force restart by holding Power+Volume Down for 15 seconds. What should you do next to isolate the issue?

A.Replace the battery immediately.
B.Connect the phone to a known-good external monitor via USB-C to test video output.
C.Perform a factory reset from recovery mode.
D.Reinstall the operating system using a PC.
AnswerB

If the external display shows content, the phone's internal display or its connector is faulty. This isolates the issue to the display assembly.

Why this answer

This scenario points to a display or backlight failure, not a total system crash. The device is operational (vibrates), so the problem is likely with the LCD, backlight, or display cable. Testing with an external display or checking for physical damage is the logical next step.

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14
MCQhard

A user reports that their laptop's built-in webcam is not working in any application. The device manager shows the camera with a yellow exclamation mark. The technician has already updated the driver to the latest version, but the issue persists. What should the technician do next?

A.Uninstall the webcam driver from Device Manager and restart the laptop to let Windows reinstall it automatically.
B.Check the laptop's physical privacy shutter or function key (e.g., Fn+F10) that may disable the camera.
C.Replace the webcam module.
D.Disable and re-enable the webcam in Device Manager.
AnswerB

Many laptops have a hardware or software toggle that disables the camera at the hardware level, causing it to appear as a problem device. This is a common oversight and should be checked before assuming hardware failure.

Why this answer

A yellow exclamation mark in Device Manager indicates a driver problem, but since updating the driver did not help, the issue may be a hardware conflict or a disabled device. The next step is to check if the webcam is physically disabled via a function key (e.g., Fn+F10) or a privacy shutter. Many laptops have a hardware switch or a keyboard shortcut to disable the camera for privacy.

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15
MCQeasy

A customer brings in a tablet that will not turn on. The technician presses the power button and sees no response. The tablet was working earlier in the day. What is the first step the technician should take to troubleshoot this issue?

A.Replace the battery immediately
B.Perform a hard reset by holding the power and volume buttons
C.Connect the tablet to a charger and wait a few minutes
D.Open the tablet and inspect the motherboard for damage
AnswerC

Connecting to a charger is the first step to rule out a depleted battery; if the battery is completely dead, it may need a few minutes before the device responds.

Why this answer

The most logical first step is to ensure the device has power; a drained battery is a common cause of a device not turning on. Checking the charge level and attempting to charge it is a simple, non-invasive test that can quickly identify the problem.

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16
MCQmedium

A technician is deploying 20 new tablets for a hospital's nursing staff. After configuring Wi-Fi and email, they find that the tablets will not connect to the corporate 5 GHz wireless network, only to the 2.4 GHz network. All tablets are the same model. What is the most likely cause?

A.The 5 GHz SSID is hidden and requires manual entry.
B.The tablets only support 802.11b/g/n on the 2.4 GHz band and lack 5 GHz hardware support.
C.The corporate 5 GHz network requires 802.1X authentication that is not configured on the tablets.
D.The tablets have a defective Wi-Fi antenna.
AnswerB

Many low-cost tablets only include 2.4 GHz radios to save on cost and battery. This is a hardware limitation that cannot be fixed with software, explaining why all 20 tablets behave identically.

Why this answer

This is a common deployment issue where the device's wireless radio supports 2.4 GHz but not 5 GHz, or the 5 GHz channel is not supported. Older or budget tablets may lack 5 GHz capability, or the corporate network may use a 5 GHz channel (e.g., DFS channels) that the tablet's radio cannot use. Checking the tablet's Wi-Fi specifications is the correct first step.

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17
MCQmedium

A user reports that their laptop's touchpad is not working after they spilt a small amount of coffee on the keyboard. The keyboard still works, but the touchpad cursor does not move. What is the most likely cause?

A.The touchpad driver has been corrupted by the liquid
B.The touchpad has been disabled in the BIOS due to a safety feature
C.The liquid has damaged the touchpad or its ribbon cable
D.The laptop's operating system has detected the liquid and disabled input devices
AnswerC

Liquid can short-circuit the touchpad's capacitive sensors or corrode the ribbon cable connector, causing the touchpad to stop working while the keyboard remains functional.

Why this answer

Coffee can seep into the touchpad connector or the touchpad itself, causing a short or corrosion. The keyboard working suggests the liquid did not reach the main board, but the touchpad is a separate component that is more exposed. The correct answer is liquid damage to the touchpad.

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18
MCQhard

A user reports that their Windows tablet's battery drains quickly even when the device is idle. The technician checks the battery report and finds that the 'System' process is using a high percentage of CPU. What is the most likely cause?

A.The battery is nearing the end of its life and cannot hold a charge
B.A background app is consuming CPU resources
C.A device driver is preventing the tablet from entering a low-power sleep state
D.The tablet's power plan is set to 'High performance'
AnswerC

A malfunctioning driver (e.g., for the network adapter or chipset) can keep the CPU active, preventing sleep. This is a known cause of high System CPU usage and battery drain in tablets.

Why this answer

High CPU usage by the 'System' process often indicates a driver or hardware issue, such as a failing battery or a misconfigured power plan. In tablets, a common cause is a driver that prevents the device from entering low-power sleep states, leading to constant CPU activity and battery drain.

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19
MCQmedium

A technician is configuring a new Android tablet for a field worker. The worker will use a Bluetooth barcode scanner and a rugged case with a built-in keyboard. After pairing both devices, the keyboard types slowly and misses keystrokes, while the scanner works fine. What is the most likely cause?

A.The keyboard's battery is low
B.The tablet's Bluetooth driver is outdated
C.Interference from the rugged case or other wireless signals is degrading the keyboard's connection
D.The keyboard is not compatible with Android
AnswerC

Rugged cases can contain metal or shielding that interferes with Bluetooth signals. The keyboard's antenna may be more susceptible than the scanner's.

Why this answer

Bluetooth interference from other devices or physical obstructions (like a rugged case) can cause signal degradation, leading to missed keystrokes. The scanner may use a different Bluetooth profile or be less sensitive to interference. The correct answer identifies interference as the likely cause.

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20
MCQhard

A technician is troubleshooting a laptop that emits a series of beeps (one long, two short) on startup and displays nothing on the screen. The laptop was working fine until the user installed a new RAM module. What is the most likely cause?

A.The new RAM module is incompatible with the laptop's chipset
B.The laptop's display cable has become disconnected
C.The laptop's CMOS battery is dead
D.The user accidentally damaged the motherboard when installing the RAM
AnswerA

Incompatible or improperly seated RAM can cause POST failures that produce beep codes. Some motherboards map memory errors to video-related beep codes. The timing (after RAM install) strongly suggests this.

Why this answer

One long and two short beeps is a common BIOS POST code indicating a video or display adapter issue. However, since the problem started after installing RAM, it is likely that the RAM module is incompatible or not seated properly, causing a memory-related POST failure that manifests as a video error code on some systems.

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21
MCQmedium

A user complains that their laptop's built-in webcam is not working in video conferencing apps. The device manager shows the camera as 'disabled'. The technician enables it, but the camera still shows a black screen in apps. What should the technician do next?

A.Uninstall and reinstall the camera driver
B.Check for a physical privacy shutter on the webcam and verify Windows camera privacy settings
C.Replace the webcam module
D.Update the laptop's BIOS
AnswerB

Many laptops have a physical shutter that can block the camera. Also, Windows has a privacy setting that can disable camera access for apps. Both are common causes of a black screen.

Why this answer

Even if the camera is enabled in Device Manager, the privacy shutter or a privacy setting in the OS (like Windows Camera privacy settings) can block the camera. Checking the physical shutter and OS privacy settings is the logical next step.

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22
MCQeasy

A user reports that their Android smartphone's touchscreen is unresponsive after they dropped it in a puddle. The device powers on, but the display shows distorted colors and the touch input does not register at all. What is the most likely cause of this issue?

A.The device's battery is swollen and pressing against the display
B.The digitizer and LCD have been damaged by liquid ingress
C.The device's operating system has corrupted due to water exposure
D.The screen protector is trapping moisture and blocking touch input
AnswerB

Liquid can short-circuit the digitizer and LCD connectors, causing both touch failure and display artifacts. This matches the symptoms after water exposure.

Why this answer

Water damage can cause short circuits and corrosion on the display digitizer and LCD panel, leading to both touch unresponsiveness and visual distortion. Powering on a wet device often worsens the damage. The correct answer focuses on the digitizer and LCD failure due to liquid ingress.

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23
MCQmedium

A technician is troubleshooting a Lenovo ThinkPad that will not turn on. When the power button is pressed, the keyboard lights flash briefly, then nothing. The battery is known to be charged. After removing the battery and holding the power button for 30 seconds, the laptop still does not power on. What should the technician try next?

A.Replace the CMOS battery.
B.Connect the laptop to a known-good AC adapter and try to power on without the battery installed.
C.Reseat the RAM modules.
D.Perform a hard reset by disconnecting the internal battery (if accessible) and holding the power button for 60 seconds.
AnswerB

This isolates the issue to either the laptop's internal power circuitry or the battery/charger. If it powers on with the AC adapter, the battery or its connection is faulty. If not, the motherboard likely has a fault.

Why this answer

This is a classic symptom of residual charge in the capacitors preventing a proper boot. The 'remove battery and hold power button' step discharges the system. If that fails, the next step is to test with a known-good AC adapter, as the internal charging circuit may be faulty.

If that also fails, the motherboard or power button may be defective.

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24
MCQmedium

A user reports that their iPhone 13 will not charge when plugged into the USB-C port on their company-issued laptop, but it charges normally from the wall adapter. The laptop's USB-C port works with other devices. What is the most likely issue?

A.The iPhone's Lightning-to-USB-C cable is faulty.
B.The laptop's USB-C port does not support Apple's Power Delivery (PD) protocol.
C.The iPhone's charging port is clogged with debris.
D.The laptop's USB-C driver is outdated.
AnswerB

Many laptops' USB-C ports are data-only or provide limited power. iPhones require a specific PD negotiation to charge. Without it, the phone may not draw power, or the port may not supply it.

Why this answer

This is a classic power delivery negotiation issue. iPhones use a proprietary charging protocol over USB-C (or Lightning). The laptop's USB-C port may not support the Apple-specific charging profile or may not provide enough power (e.g., only 5V/0.5A). The wall adapter provides the correct voltage and current for the iPhone.

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25
MCQhard

A technician is troubleshooting a laptop that has a blank screen after the user closed the lid and then reopened it. The laptop's power LED is on, and the fan is spinning. Pressing keys does not wake the display. What should the technician do first?

A.Replace the LCD panel
B.Perform a hard reset by holding the power button for 10-15 seconds
C.Reseat the RAM modules
D.Check the laptop's lid sensor for damage
AnswerB

A hard reset can resolve a system that is stuck in a sleep state or has a hung graphics controller. This is a standard first step for blank screen after lid closure.

Why this answer

This scenario describes a classic 'lid sensor' or 'display not waking' issue. The laptop is on (power LED, fan), but the display is blank. The first step should be to perform a hard reset by holding the power button to force a shutdown, then power on again.

This can clear a hung state.

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26
MCQmedium

A user reports that their laptop's touchpad is not working properly. The cursor jumps around randomly when they try to use the touchpad. An external mouse works fine. Which of the following should the technician do first?

A.Update the touchpad driver
B.Disable the touchpad in Device Manager and re-enable it
C.Clean the touchpad surface with a soft cloth
D.Replace the touchpad
AnswerC

Dirt or moisture on the touchpad can cause erratic cursor movement; cleaning it often resolves the issue immediately.

Why this answer

Cursor jumping is often caused by a dirty or greasy touchpad surface. Cleaning the touchpad with a soft, lint-free cloth is the simplest and most effective first step before considering driver or hardware issues.

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27
MCQeasy

A user reports that their smartphone's battery drains very quickly, even when the phone is idle. The phone is less than a year old. Which of the following is the most likely cause of this issue?

A.The battery is defective and needs replacement
B.The screen brightness is set too high
C.An app is running in the background and consuming power
D.The phone is infected with a virus
AnswerC

Background apps, especially those with bugs or high power usage, can drain the battery even when the phone is not in active use.

Why this answer

A common cause of rapid battery drain on smartphones is apps running in the background, especially after an OS update that may change permissions or app behavior. Checking battery usage statistics can help identify the culprit.

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28
MCQhard

A user reports that their laptop's battery life has dropped significantly over the past month. The battery now lasts only 30 minutes on a full charge. The technician runs a battery report and finds that the design capacity is 50,000 mWh, but the full charge capacity is only 12,000 mWh. What is the most likely conclusion?

A.The battery calibration is off and needs to be recalibrated by fully discharging and recharging.
B.A background process is consuming excessive power, draining the battery quickly.
C.The battery has reached the end of its useful life and needs to be replaced.
D.The laptop's power adapter is not providing enough voltage to charge the battery fully.
AnswerC

A full charge capacity of 12,000 mWh versus a design capacity of 50,000 mWh means the battery has lost over 75% of its capacity. This is a clear sign of battery wear and requires replacement.

Why this answer

The battery report shows a severe reduction in full charge capacity compared to design capacity. This indicates the battery has degraded significantly, likely due to age, heat, or charging cycles. A battery with a full charge capacity below 80% of design capacity is considered worn out and should be replaced.

There is no software fix for this hardware degradation.

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29
MCQeasy

A user reports that their Android smartphone's touchscreen is unresponsive after they dropped it. The screen is not cracked, and the device powers on normally. Which of the following is the most likely cause of the touchscreen issue?

A.The LCD panel is damaged
B.The digitizer is damaged
C.The battery is swollen
D.The operating system is corrupted
AnswerB

The digitizer is the touch-sensitive layer; a drop can separate or break it, causing unresponsiveness even if the glass is intact.

Why this answer

A drop can easily damage the digitizer layer, which is responsible for detecting touch input, even if the glass display remains intact. The LCD/OLED panel may still function for display, but without a working digitizer, touch input will not register.

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30
MCQmedium

A technician is troubleshooting a Samsung Galaxy tablet that has a cracked screen but still responds to touch. The user wants to transfer data to a new tablet. The technician connects the tablet to a PC via USB, but the PC does not recognize the device. What is the most likely reason?

A.The USB cable is defective
B.The tablet is in USB charging-only mode and cannot be changed due to the cracked screen
C.The tablet's USB port is damaged from the drop
D.The PC lacks the proper Samsung USB drivers
AnswerB

Android devices often default to 'Charging only' when connected via USB. Changing to 'File transfer' requires screen interaction, which is difficult with a cracked screen.

Why this answer

When a device's screen is cracked, the digitizer may still work, but the user might not be able to change USB settings from 'Charging only' to 'File transfer' if the touch input is needed for that selection. This is a common scenario where the default USB mode prevents data access.

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