220-1101 Mobile Devices Practice Test 12 — 15 Questions

Question 1

A user reports that their smartphone's touch screen stopped working after the phone was briefly submerged in water. The technician dried the device thoroughly, then replaced the screen assembly (including the digitizer) with a known-good part. After reassembly, the touch screen is still completely unresponsive. The display works correctly, and the phone powers on and charges normally. Which of the following components should the technician check next?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The motherboard's touch screen controller IC. Water damage can short or corrode the touch screen controller IC on the motherboard, which processes signals from the digitizer. Since the display and other functions work, the issue is isolated to the touch input path, and replacing the screen assembly (including the digitizer) did not resolve it, pointing to a damaged controller IC rather than the peripheral components.

Answer

The battery

Answer

The charging port

Answer

The SIM card slot

Question 2

A user reports that their smartphone's battery life has significantly decreased after a recent OS update. The technician observes that location services and background app refresh are enabled. Which of the following should the technician do FIRST to address the issue?

Accepted Answer

Check the battery health status in the device settings. The first step is to check the battery health status in device settings (C) to determine whether the battery is degraded or whether the OS update introduced a software issue. Battery health reveals maximum capacity and peak performance capability, which distinguishes hardware wear from software-related drain. This diagnostic step guides subsequent actions and avoids unnecessary resets or setting changes.

Answer

Calibrate the battery by fully draining it and then charging it to 100%

Answer

Disable all background app refresh settings

Answer

Perform a factory reset of the smartphone

Question 3

A user's smartphone is unable to make or receive calls. The device shows full signal bars but when attempting to place a call, it immediately ends. The technician checks airplane mode and it is off. Which of the following should the technician check FIRST?

Accepted Answer

Check the SIM card.. Full signal bars indicate the device is connected to the cellular network at the RF level, but an immediate call failure suggests the device cannot register with the network for voice services. The SIM card contains the IMSI and authentication keys (Ki) required for network registration; if it is loose, damaged, or not properly seated, the phone will show signal bars from the base station but fail to complete call setup because the network rejects the unauthenticated device.

Answer

Reboot the phone.

Answer

Check the Bluetooth settings.

Answer

Check the Wi-Fi calling settings.

Question 4

A technician is repairing a smartphone with a cracked screen. After replacing the screen assembly, the touch screen is completely unresponsive, although the display shows properly. The technician has verified that the digitizer flex cable is firmly seated in the connector on the motherboard. Which of the following should the technician check NEXT?

Accepted Answer

Check that the grounding screw for the digitizer is installed and tight. Many smartphone digitizer assemblies require a dedicated grounding screw to complete the circuit for capacitive touch sensing. Without this ground, the digitizer may receive power and data via the flex cable but cannot establish a stable reference voltage, causing the touch screen to be completely unresponsive even though the display works. The technician has already verified the flex cable connection, so checking the grounding screw is the logical next step.

Answer

Check that the LCD cable is properly connected

Answer

Check the digitizer cable for damage or improper orientation

Answer

Replace the battery

Question 5

A user reports that their smartphone's Bluetooth will not pair with their car's hands-free system after a recent OS update. The car's system has been successfully paired with other phones. The technician has reset the phone's network settings and forgotten the car from the Bluetooth list, but the pairing still fails. Which of the following should the technician try NEXT?

Accepted Answer

Check for a firmware update for the car's infotainment system. The car's system works with other phones, so the issue is likely an incompatibility introduced by the smartphone's OS update. Checking for a firmware update for the car's infotainment system is the next logical step because the car's Bluetooth stack may need an update to maintain compatibility with the new OS version's Bluetooth profiles or security requirements (e.g., LE Secure Connections).

Answer

Perform a factory reset of the smartphone

Answer

Replace the Bluetooth antenna in the smartphone

Answer

Disable Wi-Fi on the smartphone before pairing

Question 6

A technician replaced the cracked display on a smartphone. After reassembly, the touchscreen works perfectly, but the physical home button (which also houses the fingerprint sensor) does not respond to presses. The display and touch functionality are normal. Which of the following components is MOST likely the cause of this issue?

Accepted Answer

The home button flex cable. The home button flex cable is the dedicated connection for both the physical button's tactile input and the fingerprint sensor. Since the display and touchscreen work fine, the digitizer and LCD cables are intact, and the battery connector is not related to button functionality. A damaged or improperly seated home button flex cable would prevent the button from registering presses while leaving other functions unaffected.

Answer

The digitizer flex cable

Answer

The battery connector

Answer

The LCD cable

Question 7

A user reports that their smartphone's camera app crashes whenever they attempt to take a photo with the flash enabled. The camera works normally without flash, and the flashlight app functions correctly. Which of the following components is MOST likely faulty?

Accepted Answer

Camera module. The camera module is the most likely faulty component because it contains the flash LED driver circuitry that synchronizes the flash with the camera sensor. When the flash is enabled, the camera module must coordinate the LED pulse with the image capture; a failure in this integrated circuit causes the app to crash, even though the standalone flashlight app works by bypassing the camera's synchronization logic.

Answer

Flash LED

Answer

Motherboard

Answer

Battery

Question 8

A user reports that their smartphone charges intermittently. The technician observes that the USB-C cable fits very loosely into the charging port and often falls out. Which component is MOST likely causing this issue?

Accepted Answer

The charging port or connector is damaged or worn.. The USB-C cable fitting loosely and falling out of the charging port is a classic sign of physical wear or damage to the port or connector. Over time, the internal retention clips or solder joints inside the port can degrade, preventing a secure mechanical and electrical connection. This intermittent physical contact directly causes the intermittent charging behavior, not a software or battery issue.

Answer

The battery is no longer able to hold a charge.

Answer

The operating system has a bug affecting charging.

Answer

The firmware controlling the charging circuit is corrupted.

Question 9

A user reports that their smartphone's battery drains significantly faster than normal and the device feels very hot to the touch, especially during charging. The phone is using a third-party charger and USB cable purchased from a discount store. Which of the following is the BEST first step the technician should recommend?

Accepted Answer

Use the original manufacturer charger and cable. The most likely cause of rapid battery drain and overheating during charging is a non-compliant third-party charger or cable that does not meet the device's power delivery specifications. Using the original manufacturer charger and cable ensures proper voltage and current regulation, preventing excessive heat and inefficient charging that can degrade battery health.

Answer

Replace the smartphone battery

Answer

Perform a factory reset of the phone

Answer

Disable background app refresh and location services

Question 10

A user reports that their smartphone will charge wirelessly on a charging pad but will not charge when connected to a USB-C cable. The cable and charger have been tested on another phone and work normally. The technician has already performed a forced restart and cleaned the charging port with compressed air. Which component should the technician replace FIRST?

Accepted Answer

Charging port flex cable / charge port assembly. The charging port flex cable / charge port assembly is the most likely culprit because wireless charging works (bypassing the port entirely) but wired USB-C charging fails, even though the cable and charger are proven good on another device. This isolates the fault to the physical port or its internal flex cable connection, which is a common failure point due to wear, debris, or damage that compressed air cannot resolve.

Answer

Battery

Answer

Main board / motherboard

Answer

USB controller chip

Question 11

A technician replaced the cracked glass and LCD assembly on a smartphone. The touch screen now works intermittently and often registers touches in the wrong location or not at all. The display itself is clear and bright. Which of the following is the MOST likely cause?

Accepted Answer

The digitizer flex cable is loose or not seated correctly. The digitizer (touch layer) is separate from the LCD in most modern smartphones. When the glass and LCD assembly is replaced, the digitizer flex cable must be properly seated. A loose or incorrectly seated flex cable causes intermittent touch registration and ghost touches because the electrical connection for capacitive touch sensing is unreliable, while the display remains unaffected since it uses a separate data path.

Answer

The LCD is not compatible with the smartphone model

Answer

The smartphone battery is swollen and pressing on the digitizer

Answer

The smartphone's software needs to be recalibrated for the new screen

Question 12

A user reports that their smartphone will charge wirelessly on a charging pad but will not charge when connected to a USB-C cable. The USB-C cable and charger work normally when tested on another phone. The technician has already performed a forced restart and cleaned the charging port with compressed air. Which component should the technician replace FIRST?

Accepted Answer

Charging port. Charging port. Since the USB-C cable and charger work on another phone, the cable and charger are verified functional. The phone charges wirelessly, which bypasses the charging port entirely, confirming the battery and charging IC are operational. The technician has already cleaned the port and performed a forced restart, so the most likely remaining hardware fault is a damaged or worn charging port that cannot establish a proper electrical connection with the USB-C cable.

Answer

Battery

Answer

Charging IC

Answer

USB-C cable

Question 13

A user reports that their smartphone's touch screen is unresponsive. The technician observes that the screen is cracked and has visible black spots. The phone still powers on and the physical buttons work. Which of the following components is MOST likely faulty?

Accepted Answer

Digitizer. The digitizer is the layer responsible for converting touch input into electrical signals. A cracked screen with visible black spots indicates physical damage to the digitizer layer, which directly causes unresponsiveness to touch. The LCD display may still function (showing an image) even when the digitizer is broken, which matches the symptom of the phone powering on and physical buttons working.

Answer

LCD display

Answer

Battery

Answer

Motherboard

Question 14

A user reports that during phone calls, the person on the other end cannot hear them. The user can hear the caller clearly. The user can also record voice memos and videos with sound without any issues. Which of the following components is MOST likely faulty?

Accepted Answer

Noise-cancellation microphone. The noise-cancellation microphone is the most likely faulty component because it is specifically designed to pick up the user's voice while filtering out ambient noise. During phone calls, the primary microphone handles voice transmission, but if the noise-cancellation mic fails, it can cause the system to misinterpret the user's speech as background noise and suppress it, resulting in the caller not hearing the user. The fact that voice memos and videos record correctly indicates the main microphone is functional, isolating the issue to the secondary microphone used for noise cancellation during calls.

Answer

Earpiece speaker

Answer

Loudspeaker

Answer

Charging port

Question 15

A user reports that their smartphone's screen does not turn off during phone calls when held to the ear, causing unintended button presses. The screen works normally at all other times. The technician has verified the device's operating system and apps are up to date. Which of the following is the MOST likely cause of this issue?

Accepted Answer

A faulty proximity sensor. The proximity sensor, typically an infrared (IR) LED and photodetector, detects when the phone is held to the ear during a call and disables the touchscreen to prevent unintended inputs. Since the screen works normally at other times and the OS/apps are updated, a faulty proximity sensor is the most likely cause, as it fails to trigger the screen-off command during calls.

Answer

A faulty ambient light sensor

Answer

Incorrect display calibration

Answer

A damaged digitizer