There are 2 ways to retract these type of calipers, the first is to use the on board computer to enable rear brake service/pad replacement mode, the second is to unplug the electrical connector to the parking brake motor, remove 3 allen bolts from the motor, remove the motor and then using a torx bit wind the screw and then compress the caliper. the pistons on this type of caliper do not spin in the bore. This brake setup is common to German cars and is exactly the same on a tesla. when pad and/or rotor replacement is complete install parking brake motors (slight clocking of the shaft in the caliper may be required for alignment but is very easy) plug them in and cycle the parking brake a few times, it will auto calibrate and you are finished.
