You have a real problem here that only the dealer can resolve. I had the same thing happen to mine at the beginning of the year. Turns out that the screw that holds the motor in place is on the outside of the trailer. If you can get at the screw, and you can get it out, you have to pop the motor up about 3/4 of an inch and then one can manually, although it is tough, move the slide in or out. You have to do both sides also. Turns out that one of my motors rusted over the winter and froze, so only one side of the slide would move at all. Not sure what the dealer did to get it fixed, but I ended up with 2 new motors with updated gear ratios. The dealer modified the inside of the frame so that if this happens again, they can get to the motors from the inside as well as the outside.
It took about a week to get the slide functional again.
Good luck.