Benjamin Mayo, 9to5Mac:

When Touch ID debuted with the iPhone 5s, the home button became cryptographically paired with the display and logic board. Replacing an iPhone screen and digitiser without going through Apple’s proprietary calibration process would result in an iPhone with a new screen, but non-functional fingerprint sensor. The same is true with the Face ID biometric system introduced with iPhone X.

And:

Until today, Apple has needed to distribute bulky repair equipment to its own Apple Store repair centers and authorized resellers to affirm that the 3D Touch system is working correctly.

And:

Apple has now managed to achieve all the calibration steps using software alone, dropping the need for dedicated physical hardware to be installed at repair locations.

Makes me curious how they solved this problem. The good news is, screen repairs are now going to be much easier to schedule, with a much faster turnaround.