Fix Touchscreen Not Working After Screen Replacement
A technician replaces the glass/digitizer assembly on an iPhone 12. After reassembling the phone, it powers on and the display works, but the touch input is completely unresponsive. The technician has already reseated the screen connectors. Which of the following is the MOST likely cause of the touch failure?
Quick Answer
The answer is a torn or improperly connected digitizer flex cable. This is correct because the digitizer flex cable is the dedicated pathway for touch signals from the glass layer to the logic board, while the display image travels through a separate LCD or OLED data path. When the digitizer cable is damaged or not fully seated, the screen will light up and show content, but the phone will completely ignore finger taps and swipes. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your understanding of modular smartphone repair and the distinction between display and touch subsystems—a common trap is assuming reseating the main screen connector fixes everything, when the digitizer cable often has its own separate latch. Remember the memory tip: “Display shows, digitizer touches”—if one works without the other, trace the cable that’s missing its signal.
⚠ Common exam trap
Watch out — candidates often assume reseating the screen connectors covers all connections, but they overlook the separate digitizer flex cable that is easily torn or left unseated during glass-only replacements.
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
✓
The digitizer flex cable was torn or not properly connected during the repair
The digitizer flex cable is responsible for transmitting touch input from the glass/digitizer layer to the logic board. If it was torn during the replacement or is not fully seated despite reseating the main screen connectors, the touch function will fail while the display (which uses a separate LCD/OLED data path) still works. This is the most common physical failure in iPhone glass/digitizer replacements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The digitizer flex cable was torn or not properly connected during the repair
Why this is correct
Touch input travels over the digitizer flex cable, a separate path from the display flex. Since the screen shows an image but registers no touch, and connectors were reseated, a torn or improperly seated digitizer flex is the most likely fault.
- ✗
The replacement screen is not a genuine Apple part and is incompatible
Why it's wrong here
Non-genuine screens usually still register touch; the iPhone 12 pairs the digitiser to the logic board, so a transferred original screen or serial-number programming is needed. Third-party parts are tempting because they cause True Tone and battery-health warnings, but those are cosmetic, not touch failures.
- ✗
The touch controller integrated circuit on the logic board is damaged
Why it's wrong here
Logic-board touch-controller damage would require board-level repair, yet the failure began only after the screen swap, pointing to the digitiser connection instead. Blaming the logic board is tempting when connectors are reseated, but that IC is the correct suspect only after liquid damage or a drop.
- ✗
A software glitch occurred during reassembly that disabled the touch screen
Why it's wrong here
A software glitch cannot disable touch when the display still renders, since iOS loads the digitiser driver regardless. Reflashing or restoring is tempting as a quick fix, and it would be correct if touch failed after an iOS update, but here the fault appeared immediately after hardware reassembly.
Go deeper
Related to this question
Learn chapter
Laptop Keyboard and Touchpad Replacement
Key term
Organic Light-emitting Diode
An Organic Light-emitting Diode (OLED) is a display technology that uses organic compounds to emit light when an electric current passes through them, enabling thin, flexible, and energy-efficient screens with high contrast.
About these practice questions
One of 896 original 220-1101 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on 220-1101
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is replacing a cracked screen on an Android smartphone. After reassembling the device, the phone powers on successfully and the display shows the lock screen with the correct time and background image. However, the touchscreen does not respond to any taps or swipes. The technician has verified that the replacement screen is compatible with the phone model. Which of the following should the technician check FIRST?
medium- ✓ A.Reseat the digitizer ribbon cable connector on the motherboard
- B.Reconnect the LCD display cable
- C.Replace the smartphone battery
- D.Perform a factory reset from the recovery menu
Why A: The touchscreen not responding while the display works correctly indicates a problem with the digitizer, not the LCD. The digitizer ribbon cable connects the touch sensor to the motherboard; if it is loose or improperly seated after reassembly, the touchscreen will not register input. Reseating this connector is the logical first step before considering other components or software resets.
Variation 2. A technician replaced the screen assembly on a smartphone. After reassembly, the phone powers on and displays correctly, but the touch screen is unresponsive. Which of the following should the technician check FIRST?
easy- A.Reboot the phone into safe mode
- B.Update the touch screen drivers
- ✓ C.Ensure the digitizer ribbon cable is properly seated
- D.Replace the screen assembly again
Why C: The digitizer ribbon cable connects the touch-sensitive layer of the screen to the motherboard. If it is loose or improperly seated after reassembly, the touch input cannot be registered even though the display (LCD/OLED) works fine. This is the most likely cause given the recent disassembly and should be checked first before any software or replacement steps.
JA
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.