iPhone X features vertical lines on the screen and keeps restarting? iPhone keeps restarting and error 9, 14 and 40? How to narrow down the fault possibilities by ruling out one by one? How to confirm the fault and fix the problem? Follow us and learn how to fix this problem step by step.

First, we need to confirm if the fault has anything to do with the screen. Get a new iPhone X display assemblyinstalled. The problem still remains the same as described earlier. We can confirm now that the fault is related to the motherboard.

The next thing we do is to confirm if the fault lies on the display circuit. Run diode mode measurement of the display connector, and measure the working voltage of the screen. All measured value is normal.
Judging by this, the fault has nothing to do with the display circuit. It is probably related to PP_GPU_SRAM or CPU.