I guess my first question is, does the motor have power? Can you hear it try and run when you open or close the door?
If the motor has power and tries to operate, you might what to check this. Could the steps be binding putting pressure on the system which will shut if off. The pivot points on the steps may be dirt and need lube of some type. Have you gotten underneath and looked to see if the motor assembly was still attached to the frame. The reason I asked that was last year my steps stopped working but the motor was running. I looked underneath and the four screws holding the motor assembly had become loose and sheared off.
Good Luck