Chosen Solution
This is not your common “home button doesn’t work after screen replacement”. No, unfortunately my problem is a bit more mysterious. I’ve got an iPhone 6S with a faulty home button. I’ve replaced it with a replica part, knowing that touch-ID will not work, but alas, even the replacement button does not work. My guess is the screen needs to be replaced as that is the part that signals the button data to the motherboard. My question is: can the problem be anything else than the screen?
It can be connection to the motherboard. Take a magnifying glass and check the connector for any damage. Then clean the connector with a soft brush. If that doesn’t work my guess is a defective screen. I have had this happen a couple of times. It’s rare but it does happen. Hopefully the part has a warranty. I would also check the connector on the home button and screen connection before trying another screen. If that doesn’t fix it you could have knocked off a resistor on the motherboard by the connector but I highly doubt it. MAKE SURE YOU UNHOOK THE BATTERY WHILE TAKING OFF AND HOOKING UP THE SCREEN. You can cause a short and why take a chance.
