I think i'd start by testing for power at the motors. Its possible the wires in the door jam are broken or the main switch module is crappin out. Pretty sure all power is routed through the main driverside switch.

usualy when the motors or the regulators go out they are slow for a while and will go part way then stop, then after cooling will move again. With a bad regulator you can usualy hear the motor still moving in the door.