How to fix iPhone 6S screen turns black after white Apple appears

The iPhone 6S LCD screen turns black after white Apple logo appears, what's going on? Sometimes the iPhone 6S can enter the IOS system, but sometimes not, it's abnormal. How to fix it?

First, connect iPhone 6S to the computer via iPhone lightning cable, and then use iTunes to flash it.

At the first time, the iTunes reports unknown 4014 error when the first flash progress bar goes finished, in this case, it's not the problem of the iPhone Nand flash. According to the repair experience, we know that the damaged external configuration also can cause this error. Take out the external configuration, just flash the iPhone motherboard, but the trouble stills the same.

The co-worker feedback that the iPhone lighting cable has some problems, we need to flash the iPhone 6S for several times. So, we decided to flash the iPhone again. In this time, the flash process is successful. But we don't think the problem was solved, because the customers also said the iPhone 6S can be entered the IOS occasionally. Activate the iPhone and test the functions to check if they are normal.

After testing, all functions tested are normal, it's so weird, now we are going to recharge it. After half an hour, we test it again. The iPhone 6S has no response when we press the iPhone power button, the iPhone display screen is black, but there is a backlight.

The iPhone display screen is black when it in charging, is it the problem of the charge tube? But the charge tube won't cause this trouble.

We suspect it's problem of the iPhone USB IC. Replace the iPhone USB IC, and then power on iPhone to test, now the iPhone 6S can enter the IOS normally.

Test it for several days, the iPhone 6S LCD screen works normally, and it can be turned on smoothly, the there is no iTunes error when flashing.