BMW X3 Transfer Case

Does anyone here have experience with the transfer case of the xDrive system?

A good friend replaced the transfer case in an X3 because the bearings were defective, which damaged the gears of the control motor. A replacement actuator motor was also installed.

"I'm having trouble with the calibration; it keeps failing. The technician recommended updating the control unit. I've already done the update, but when I try to code the control unit for the transfer case, I get an error message and it stops. We've already swapped the actuator motor with a working one and even installed a different transfer case, but nothing changes. I've also checked the wiring between the control unit and the actuator motor. It seems like the control unit itself might be the problem." But why would this defect occur after a mechanical failure in the transfer case?