1. Door switch may be indicating the entry door is open. Bypass switch electrically or try sticking a magnet on the mechanism. Magnet switch is a normally open switch. Magnet can be lost and it thinks the door is open.
2. Try removing the step fuse and waiting two minutes. Be sure to ohm the fuse while out. This may reset the step controller.
Assuming you have a Kwikee Step, here is a link to manuals
https://www.lci1.com/support-kwikee-steps
Let us know what you find.
Good Luck!