Aloha,
I'm an electronics repair guy here in Hawaii. I have had problems in the past with the Touch ID not working after a repair. I have repaired them by installing a new home flex. The entire plate on back of LCD plus the home flex cable. I have done the repair with and without the small plate mentioned above. I always transfer it but I have made one work without it. I feel that the male end where the button connects is very fragile. If you don't heat the glue before removing your odds of damaging it are high. If you have damaged it buy a new back plate with home flex and it should get you going again.