Mine did that for about half a day and then went back to normal..I have since had the centre console off to investigate but found no wires off or split?..Have you tried wiggling the switch up and down a couple of times..The switch could be sticking..Ziga
Took door card off and used magic screwdriver. Gave the end of the motor a talking to and it worked. Must be dirty contacts in motor I suppose. Panic over. Can secure car now (It's parked outside)
Did you try running a direct pos and neg wire to the motor? That's what I would do first to see if it is an issue in the wiring or the motor. If that doesn't work you'd need to disconnect the motor from the "arms". Not the easiest task with the window down.