If slide working and closed, open 1/2 way and see if you can find motors, get brand/ model and search online/ download pdf OWNER/SERVICE MANUALS/ PARTS LIST? IF MOTOR/GEAR drive, some release the brake when you Unplug motor (access from below?)
Emergency Procedure MAY ONLY relate to retracting. (Some) might use a cable and cordless drill? Some, may need to remove motor, or remove a SHEAR PIN.
YES, BEST/ SMARTEST= LEARN IN THE DRIVEWAY and practice, so that you KNOW/have whatever tools needed? Good Luck.
(TerryH.) 2000-GS Conquest Limited 6266 Class-C 99-E450SD V10