Troubleshoot: iPad 4 doesn’t turn on after replacing the screen

Here is an iPad 4 need to be repaired, this iPad 4 doesn't turn on after replacing the iPad LCD screen.

Trouble Phenomenon

The iPad screen was broken, so the iPad user try to replace it, but because the wrong operation, it causes the iPad LCD screen to be half brighter and half black. So, he try to fix it by repairing iPad motherboard, but because the wrong operation, the iPad doesn't turn on.

Troubleshoot

First connect iPad to the DPS DC power supply to check the current, we found the iPad is short circuit 3A.

Remove the iPad motherboard, and then put it under the Stereo Zoom Microscope to observe, we found the inductor L2210 and L2200 and the one side of an inductor is connected by tin.

Clean it up, and then measure is again, now the iPad is not short circuit. Check iPad schematic diagram through by WUXINJI Dongle, we found these 2 inductors are backlight fuse inductor.

According to our repair experience, we can short connect these inductors by jumper wire.

After short connection, the current measured is normal. We can install the iPad now.

Press the iPad power button, the iPad is turning on smoothly. After get into IOS, the iPad screen displays normally. Test all functions on iPad, all works well.