The motor is in the trunk, left side top, behind the carpeting panel just ahead of the antenna. It turns a cable that runs to the sunroof. The roof can be opened manually by turning the big nut facing you, with a tool/socket that may still be in your toolkit. You might try opening it manually to verify if the cable and track mechanisms are the problem...be careful, in case the cable gets buggered up, as replacing this looks like a real PITA job!
Of course, check the fuse (#16 I think), and the plug connection at the motor. The black wire to the switch should be power from the fuse. I'm not much on reading MB electrical diagrams, but it looks like the blue wire is power to close, green is to open, and standard brown for ground (...and why would anyone want to open the sunroof on PEI in January anyway ??)

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1986 560SL
2002 Toyota Camry
1993 Lexus