"If you go to tour Touch ID settings and the option to turn on is greyed out, then the phone is not recognizing the Touch ID sensor. It will still work to go to your home screen, but not for fingerprint recognition.
Good news if you still see the option to turn it on and off.
Typically this is caused while the battery was plugged in or phone turned on while replacing the screen.
So, if you hard reset the phone it will usually fix this problem. If that does not, turn the phone off, disconnect and reconnect the battery, then plug in the sensor and turn the phone on. That will fix the Touch ID unless the ribbon itself has been damaged."
Is there any method to identify Touch Id not working because software error or hardware failure? On my Iphone 5s still can acces touch id menu & add fingerprint, but next step nothing happen. it seem that my finger didnt trigger touch id to read my finger. I try to do soft&hard reset, restore IOS 10.2.1, nothing to work