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.
The simplest check is also easy. Under the step is an amber light. WATCH the light and have someone OPEN and CLOSE the door with engine running. IF the light goes ON and OFF with the opening and closing, the wiring is OK and the probable failure is the step motor. SAME procedure with engine running and opening and closing the door. Tap(bang) on the step motor with a hammer. IF the step then functions the motor had a dead spot in the armature and needs replaced. It will probably work after you do this but WILL fail again. Doug
Fuses are commonly located adjacent to the battery disconnects. Operating the battery disconnect by helper while you listen for disconnect operation helps in locating it. Did you test the fuses or just look at them?