IPhone white screen what to do?

Hello guys I recently bought a case assembly for my iPhone so to make it look new again upon receiving it I installed my mother board and screen. When i turned it on displayed fine but when i wanted ti pit the screen back it made a distorted display and went white Now it only turns on white so I put the motherboard back in the old case and now it only shows the white screen and digitizer doesn't work. Everything works, charging, connecting to the computer

You have to press the on and central buttons at the exact same time and hold them for a few seconds. The screen should reload and you are good to go.

There's probably a loose connector, thats the only thing i can think of. Make sure the cables are slotted into properly.