The TouchID cable and the connector interface at the logic board is where you need to check. The cable could have a tear severing one of the lines, at the connector a pin connection could be damaged either by being a bit hard prying it off or pressing on it without aligning it properly before pressing it on with a light touch.
Hopefully you can fix the damage which is still not easy! If you can't repair your options are only replacing the logic board as the button ID key is perm bonded to the given logic board (you can't replace it on its own).