18 February 2016Apple Support:
After you try to update or restore your iOS device in iTunes on your Mac or PC, you might see error 53 in iTunes and “Connect to iTunes” on your device. Error 53 appears when a device fails a security test. This test was designed to check whether Touch ID works properly before the device leaves the factory, and wasn’t intended to affect customers.
For anyone who experienced error 53, Apple has released an update to iOS 9.2.1 to allow you to successfully restore your device using iTunes on your Mac or PC. Use the steps in this article to restore and recover your device. If you believe that you paid for an out-of-warranty device replacement based on an error 53 issue, contact Apple Support to ask about reimbursement.
Crucially, if you have a non-matching aftermarket Home Button repair, Touch ID still will not work for security reasons as it cannot be successfully validated against the iPhone internal components.
I think this is a great, speedy, response from Apple that adequately addresses what people were complaining about. To make it plain, users are no longer left with a bricked phone following an aftermarket device repair.