some of them do that.. some more often than others.
usually if you take a hammer and whack it, it will work again... until next time.
ive had 3 units over the years with power steps, and 2 of them had issues that could not be resolved without being whacked with a mallot...
maybe its something within the motors, which I never replaced, but its not due to misalignment as all linkage was always loose and free to move.
and when testing with an electrical tester, all circuits were found to be working correctly, with a good ground.
the motors are pretty dependable and Ive never heard of one burning out, but I have shown others the mallot trick on their units....
this is not always the trick, but when its not a fuse or switch failure, this almost always works.
if the unit is under warranty, let someone else try to figure out why it happens.