Kwiki steps frozen?

My steps are old and rusting. I use PB Blaster as a lubricant. That said, I'd be more inclined to believe, due to cold weather and winter hibernation, that your batteries are a little low in charge. I'd let it warm-up a bit and put a charger on the batteries before I'd worry about some mechanical issue.
Moisture freezing could also be contributing afterall, have you ever had a power window freeze in the "up" position? Same motor in use here.
It's been a long, cold winter and mechanical components may be a little bit cranky when trying to bring them back to life.

I use lithium spray grease on all the joints on my steps. Silicone does not really lubricate thoroughly and is not recommended by Kwikee. I am also not interested to see of my steps are working at these temps. Today it is warming up to +23.

It's possible you have dirt in the joints of the steps.

I had a similar problem, but it didn't freeze. The steps didn't work properly. It was the dirt that collected in the joints. You can blow it out with compressed air, when (if) it ever warms up.

The dirt will attract moisture and, will freeze.