March 8th 2017
By Mike Flaminio
According to those people, the calibration machine is a microwave-sized device that costs tens of thousands of dollars and has a mechanical arm that can run the iPhone through a battery of tests to make sure it's working properly. More interestingly, the calibration machine can change the settings on the iPhone to allow Apple to replace broken Touch ID buttons, which is impossible outside of Apple.
The article says that the machine allows Apple employees to swap out broken screens without replacing the TouchID. Last fall though, when I had a broken screen replaced, my understanding was that the sensor was replaced. Also, a while back there was an issue with a new security feature of iOS that would disable devices with an unauthorized repair to the TouchID. So, not sure exactly what's going on or if this is a recent change.
Anyway, if such a machine exists, it likely will be a subject of right-to-repair legislation that's popping up around the U.S. If it's impossible or unusually difficult to repair iPhones without this proprietary machine, Apple may have to sell the machine to repair operators to comply with some legislation.