Chosen Solution
So I bought a used iPhone 6 with a non-working flash and rear microphone. Knowing they are both on the same flex cable (power button) i replaced that cable. This did not fix the problem. I took the just removed flex cable and plugged it into a different iPhone and the flash and microphone worked. So I have narrowed the problem down a bit. It’s not the actual flash or microphone or their flex cable. Note: the power button has always worked with either flex cable. I did a complete iPhone restore with no result. Any ideas? I’m open to soldering and logic board repairs. I want to learn how to do that kind of repair so let this be a project phone for now. Thanks in advance.
U1602 chip is responsible for rear flash. Check chip under microscope to see if it has pooped out any solder balls or anything of the like - any obvious burns or marks etc. Would be almost impossible to tell if that chip is the problem without replacing it, you can order off ebay for about 7USD and try. Good luck! As for rear microphone, can’t help you there.
