If the slide out does not move upon pushing the button, don’t panic. The first thing you want to do for a slide out that doesn’t move is to check if it is getting power in the moving mechanism. You can do this by checking the circuit breaker for a blown fuse. First check the breaker or fuse panel, if everything checks out there check the battery compartment and the wiring harness near the motor that drives the slide mechanism.
If the motor sounds like it is straining to work and the lights dim when the slide out button is pushed, voltage is low or the mechanisms are binding. Look at the bottom of the mechanism to see if there are any corroded, broken or damaged parts.
If you have checked everything that could possibly be wrong and are still stumped look to see if there is a manual override. This is designed as a backup to operate the slide out system in mechanical failure. Usually a manual override in a hydraulic system will require the pressure to be released in the ram by opening up the valve and then either pushing or pulling the slide out room open or closed. Simple mechanical systems will have a hand crank, but the motor may need to be removed to turn the gears. If the slide out is on a cable system there will be an adapter to set up a drill to act as the motor. To discover what type of slide out system your RV has and how to manually override the motor look in the owner’s manual.
When renting an RV with slide outs make sure that you are familiar with how the slide out system is operated by asking someone on the rental team. They will be happy to show you the ins and outs of the particular RV you will be renting if you are not familiar and answer any questions you may have.