Chosen Solution
Hi all, So spent some time hunting and cant seem to find a definitive answer. So just replaced an iPhone 8 screen, phone boots normally and with normal brightness, then after approx 10 secs the brightness falls and can just about make out the screen contents. Brightness settings are still on full when this happens so cannot increase brightness. Re-installed the original screen and no issue at all works perfectly. I thought maybe a bug but that seems to have been fixed with the iOS updates so did a hard reset, still the problem persists. Any help will be appreciated Thanks
If the original screen works fine then it sounds like a bad replacement screen. Contact your supplier and have them replace it under warranty.
I would say the front facing camera is either damaged or not placed correctly. The camera flex includes the lighting sensor.
