Chosen Solution
I have fixed 3 different iPhone 6 screens and after all the repairs, I have a check list, see if the touch ID is working, check the ear piece, make sure screen is in perfect condition, and check both cameras. When ever I check the cameras the back Camera works but the front camera (Selfie Camera) never seems to work. I figured oh maybe it was just a faulty part, but 3 times in a row I guys im doing something wrong. Is there something wrong i’m doing like a reset or something.
You probably damaged the FFC (Front Facing Flex Cable). That cable controls the ambient light sensor, proximity sensor, front facing microphone and camera.
Not to be that guy, but try a hard reset if you haven’t already. I’ve come across that a good few times. Make sure you have no power running through the device while you’re doing this too.
