I had that issue twice. Once in a 5er when a washer from within the gear box became lodged between 2 gears. Another time, which came on gradually was caused by the slide awning roller binding. It would start, but that was it. The tech had a hard time finding it, until he removed the awning.
First check your fuse.
Most coaches have a slide controller that allows for electrical adjustment, to adjust the power in and out. It is located in some out of the way location. Like under a drawer or in the back of a cabinet or closet.
MADP, Jeep, Blue Ox, SMI AFO, Solar: 900w/672a, Amish cooling unit, Lifetime: SKP & Days End