If there is power going to the steps and they will not retract then I would get me a small hammer and tap around the hinges and spray with some good penetration oil. Remember they are exposed to the weather, rain road dust and everything, so regular cleaning and lubrication is needed If this does not work, go to next step.
Start by checking to see if the power motor is working, if so start working your way down to the steps. Be sure to check the connections on the wire and see if they are dirty or corroded , if so clean. then go to the cleaning of them.