Apple has issued a small update, iOS 9.2.1, to fix devices affected by Error 53. The company also apologized for any trouble that "Error 53" has caused customers. TechCrunch:
We apologize for any inconvenience, this was designed to be a factory test and was not intended to affect customers. Customers who paid for an out-of-warranty replacement of their device based on this issue should contact AppleCare about a reimbursement."
This update will not re-enable Touch ID, as doing so could pose a security risk if you've had your phone repaired with a third-party Touch ID sensor.
If you've been affected by "Error 53", let us know how Apple's new update is working out for you below in the comments.