We recently carried bicycles on the back lid of our 1998 Mercedes wagon and didn’t remember that the rear wiper was turned on. It then hit the bike rack and stopped never to move again. Was this fatal to the wiper motor or is there a reset? The dealer is very proud of its wiper motors.

Did You Check The Owner’s Manual For The Location Of A Rear Wiper Fuse?
That’s Where I’d start. Find and look at that fuse. Replace it if it’s blown.

Does it do anything when turned on? Try turning it on and gently try helping it move. Does it try to go or is it “dead”?
With the engine off and the wiper on, can you here the rear wiper motor running?

if the motor still works but the arm does not move the splines on the arm are stripped.

I had checked the fuse and the motor makes no noise. Does anyone know if there is an overload condition or do I need to get a new motor?