Hey Anders, the touch ID functionality will not work if the button flex cable is damaged. It also is paired with the board (so unless you can micro-solder the original chip from the flex onto a new flex, it will not work, this is what apple specialists do when you take it to them.) Try cleaning the contacts with isopropyl alcohol, if it doesn't work, your best and only bet to save it's functionality is to cough up some cash and take it to Apple, if you deem it worth it.