It could be something as simple as your ground wire that goes to the battery has come loose. The slide outs on most RV's have to have a ground wire. Try cleaning the battery terminals and see if any wires need replacing.
Mom had a problem similar this summer. Check your drive pins in the drive slide mechanism. You have to get underneath your recreation vehicle and find access to the drive gears. Two man project. You gotta have someone inside to manage the slide out switch while you watch the pins.
First make sure your battery is fully charged and that there are no signs of damage to the actuator, motor or rails. Double check all wiring to make sure everything is wired properly and the connections are secure. Modify the position of inner rail to the gear spur on assembly.