Chosen Solution
I recently changed iphone 6s with a refurbished screen. The proximity sensor didnt work so I scratched out the area that allows in light where the proximity sensor sits. Now the screen seems to not handle bright lights. When powering up there is no white apple logo screen. The phone still works, but i can only set the brightness to a certain level, or the lcd will go black until the phone is reset. Auto brightness has to be turned off. I assume where i scratched the area where the sensor sits is the culprit. A new screen should fix this right???
If the display blacks out then this would mean either the backlight circuit on the board is not functioning properly (providing enough power to the screen’s backlight) or it is a bad replacement screen. I would try the old screen if it still works just in case. Have you made sure to leave battery disconnected when unplugging or plugging in the screen cables? As the backlight circuit is very easy to damage on this model when the battery is left plugged in.
The sensor has to let a certain amount of light through too much and it wont work correctly, u may have another issue with the backlight as well as mentioned above… To test the sensor try getting a black felt tip marker and just painting over the front of the screen where the sensor is making it darker again may make the sensor work if it’s not a faulty sensor altogether.
