Just to add my FP works fine so not willing to risk trying this ,but some one having issues it could be the answer
The calibration tool, by the looks of it, only tells the system that the new module is verified (by the user). This is because the phone, strictly speaking, doesn't know much about the (black box) fingerprint reader. The reader itself just sends its "signature" (most likely a serial number or something similar), how many fingerprints are registered, and the phone can request a read (which either returns recognised, not recognised, or faulty/impartial read), or a registration.
Simply said, the phone does not have access to the raw fingerprint data, for security reasons. But this can mean that if someone replaces the FP reader with one that has different fingerprints loaded, they could abuse that and unlock your phone with their own finger. By disabling the FP reader when an unknown signature is detected (i.e. you, or someone else, replaced the screen), the user is notified about the change, much like the warning screen during boot if your bootloader is unlocked.
The calibration tool, as such, is the user's way of telling the OS that yes, you've authorised this replacement. It shouldn't make the existing FP reader better or worse.
