White screen when put to sleep

After replacing the vibrate motor in my iPhone it has a white screen when woken up from sleep, the only way around it is to reboot. ( Home button + Power button ) I've tried everything from restoring it,

( both in DFU and normal )

and all kinds of button combinations.

Removing the mainboard for an hour.

The phone works normal, if I set the auto lock to never. I've read that it could mean a bad LCD, but why would it show a white screen after locked but work normally when not locked ? Could it be because I didn't turn the device off when unplugging the display ? ( The screen was off though when I did it.)

All the cables are connected properly.