Kwickee's can be frustrating at times. Don't know if you have a magnetic or a physical switch.
If magnetic, there should be a magnet on the door frame which contacts a magnetic (reed) switch (either visible or maybe built into the frame..or whatever.) Try a another magnet (any sort) on or around where the magnetic switch is ..if it works the original magnet is either stuffed or mislocated.
If not working either a wire to the switch or the switch is faulty.
A physical switch operates when the door touches it by pulling or pushing the switch...in both cases the power generally run from the controller to earth via the switch. Alternate is maybe both wires on switch run to controller. The wire you mentioned is maybe the earth or maybe the one to the controller - ascertain which it is as you may be chasing the wrong one.
Replacement magnetic reed switches are less than $10 at Home Depot..google images for more info.
Take care when playing with the steps...the steps mechanism may appear slow but it has the potential to amputate a hand or arm if in the wrong place at the time.
1995 35' A Class Australian built "Classic Freeway"
Cummins 6B intercooled turbo pusher, Allison 4 spd on Spartan Chassis