Take the key out of the ignition.
Hi, I just inherited my Aunties 26' Lexington and drove it from Georgetown, TX to San Diego with the step out because it wouldn't go in. When I got it home, my husband was an automotive electrician and was able to take the circuit board out and fix it so it would go in.
We tried all the switches to make it stay out when it was parked. We finally realized that when we took the key out of the ignition the step would stay out. So hopefully you can just take the key out and it will work. The switches on the bottom by the step were for outside lights on our model.