If neither side is moving up or down, check where the motor attaches to the leg inside the front cargo compartment. It's possible that the bolt connecting the motor to the spindles has fallen out. If so, you just need to replace that bolt and the motor can then move the legs. Also check the other side, there is a bolt for that side also.
If all seems, OK, then it's probably what happened to us...a gear in the motor has stripped and the motor will need to be replaced. As said earlier, you should have a handle to manually crank the legs up and down. We had to do this, if you do, have someone push the button to extend the legs while you crank...it makes the process much easier.