Chosen Solution
I have ordered a complete, assembled display replacement (display, touch, earpiece/mic/etc. already installed, only needed to put it touchID home button), and the ambient light sensor won’t work. As some have mentioned, for the auto-brightness setting, they get the text in the accessibiliy/display accomodation settings, but not the actual on/off switch, hinting at a “missing” sensor (or what the software deems as not working sensor). The rest (proximity sensor, front facing camera, earpiece) do work just fine though. Is it possible that the assembled display unit came broken, or is there something else I missed to do/check/change? Thanks! Settings screenshot for reference: https://imgur.com/a/rNSUw
It may have to do with the screen or the sensors. If you have checked if the cables are properly connected, and it works fine with another screen on it. You most likely received a defect assembled display unit.
Sometimes the software just not recognise the new hardware. Put your phone to DFU mode, reset and update the software through iTunes. If the auto brightness not damaged it will solve your problem.
