220-1101 Mobile Devices Practice Question
A user's smartphone has become intermittent: the screen flickers and sometimes goes completely black for a few seconds before returning to normal. The phone has not been dropped recently and there is no visible damage. The technician has already performed a soft reset and the issue persists. Which of the following is the most likely cause?
⚠ Common exam trap
Test-takers frequently confuse a loose internal display cable with a failing battery or corrupted OS, because intermittent power-related issues can mimic display problems, but the specific symptom of the screen going black and returning to normal points to a connection fault, not power delivery or software corruption.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Loose internal display cable
The intermittent screen flickering and blackouts, without physical damage or drop history, strongly point to a loose internal display cable. A soft reset did not resolve the issue, ruling out temporary software glitches. The display cable connects the screen to the motherboard; if it becomes slightly unseated due to thermal expansion or vibration, it can cause intermittent signal loss, leading to the described symptoms.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Failing battery
Why it's wrong here
A failing battery can cause voltage ripple or sudden shutdowns under load, but it rarely produces a flickering display because the display circuit is typically isolated from the main power rail until it reaches a critical low-voltage threshold. In smartphones, characteristic battery failure symptoms are unexpected power-off at moderate charge, charging anomalies, or slight swelling, none of which explain a screen that intermittently loses image integrity while the device remains powered on. Even a degraded battery with high internal resistance would more likely cause a reboot loop than a flicker, since the screen's backlight and TFT driver receive stable voltage until the main power collapses.
- ✓
Loose internal display cable
Why this is correct
A loose internal display cable is the most likely cause because smartphones use thin flex cables with zero-insertion-force connectors that can gradually work partially out of their sockets over time. Any micro-movement, such as pressing the home button or a drop, can momentarily break the display data lanes, causing the screen to flicker or go black before re-seating itself. This intermittent, position-dependent behavior is classic for a connection problem, and re-seating replaceable flex cables is a standard repair step after ruling out external damage.
- ✗
Corrupted operating system
Why it's wrong here
Corrupted operating system firmware typically presents as persistent software symptoms like boot loops, random app crashes, or a frozen 'bootloader' screen, because the display driver itself is part of the kernel and would either load or fail as a whole, not intermittently after the system stabilizes. A single corrupted graphics driver might stutter or produce graphical artifacts, but true flickering that comes and goes independently of software load is almost always electrical or mechanical in nature. If the OS were causing the flicker, it would likely be accompanied by error codes or a full system restart, and a backup/restore would resolve it, which is not characteristic of this symptom.
- ✗
Faulty digitizer
Why it's wrong here
The digitizer is a separate transparent layer responsible for capacitive touch sensing, while the actual image is produced by the underlying LCD or OLED panel plus its backlight. A faulty digitizer would produce phantom touches, unresponsive zones, or touch lag, but it has no control over pixel presentation or scan-out timings, so it cannot directly cause screen flicker. Confusion arises because the touch screen and display are often laminated as one assembly, but electrically they are separate; damage to the digitizer alone would not disrupt the display signal path.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.