This is definately a first. Seeing all kinds of issues with 3D printers, I never had a stepper motor failure.
I started to get failed prints experiencing massive layer shifts like this accompanied by crash detections:
Manually moving the y-axis already revealed the problem, dissassembling the drive belt showed that the stepper motor was getting stuck, not rotating freely.
Disassembly of the motor further narrowed down the problem to one of the bearings having failed.