The calibration measures only when the screen is open and closed. There is a grace period of a few seconds to allow you to close the screen.
But yes, if you don’t do it correctly, you will burn the service part and have to replace it again.
But yes, if you don’t do it correctly, you will burn the service part and have to replace it again.
From that perspective making it one-time programmable is not unreasonable.
Though it could be simpler if it was something like a magnet on the lid that activates a magnetic switch on the bottom part (and it would be harder to have a false negative result). But Apple is going to Apple