I had that problem with mine. It was the control board on mine. You can check 12 volt power to the control board with a check light or meter (better option). If you have 12 volts going into the board but nothing out, that is probably your problem. A bad ground will also stop all operation. There's a lot of road grime, dirt, etc that gets on the ground and may stop the operation. If you're not getting 12 volts to the control board then you need to look for a fuse somewhere.
If it's the control board, it's a pretty easy fix for about $80. I replaced everything, controller, motor and gear linkage for about $200.