Many users are experiencing error 53 on iPhone 6 & 6S iPhones. This appears to have been caused by a 3rd party repair or damage to the fingerprint/home button. There is no cure yet and Apple suggest you buy a new iPhone.
Apple’s recent response: “This is a security feature to protect their clients – We protect fingerprint data using a secure enclave, which is uniquely paired to the Touch ID sensor. When iPhone is serviced by an authorised Apple service provider or Apple retail store for changes that affect the Touch ID sensor, the pairing is re-validated. This check ensures the device and the iOS features related to Touch ID remain secure. Without this unique pairing, a malicious Touch ID sensor could be substituted, thereby gaining access to the secure enclave. When iOS detects that the pairing fails, Touch ID, including Apple Pay, is disabled so the device remains secure.”
Appel have not been replacing or removing Touch ID button on iPhone 6 or 6 Plus, in the knowledge that problems can ensue. We can only suggest that anyone with an error 53 contact an AppleStore with their fingers crossed.