Chosen Solution
I have just replaced my screen on my iPhone 6S after half of the old screen stopped responding to touch. In what I now realise was a mistake, I did the swap with the phone on and the home button that came with the new LCD assembly. When I realised the new TouchID home button wasn’t working I then swapped it for the one off the old LCD assembly. Now when I turn on my iPhone I get the message: “touch id unable to activate touch id on this iphone”. From my research it appears as though the TouchID button registers itself with the phones OS and if the OS has detected that it has changed then it stops working? My issue here is that I don’t know how to overcome this.
when you put the old home button in to the new screen, does it function like a home button? the factory home button is matched to the motherboard, so if you replace home buttons, you will lose touch ID. putting back the original button should restore Touch ID functionality. if this is not the case, then you should carefully inspect the ribbon cable of that button for any damage that may have occurred when it was removed from the old screen. try disconnecting it and reseating the connector. if the home button works, but touch ID doesn’t, then chances are there was some sort of damage to the button, in which case, you’re SOL as far as Touch ID goes. sorry.
