Stuck open, or trying to open it?

Blue, 25 A fuse?

Does the fuse blow when you try the switch, or blow spontaneously like there's a short upstream of the switch?

If it happens when you try the switch, then unplug the motor and try the switch. If it doesn't blow, then the problem is probably within the motor or drive mechanism.

Since you can't get it to budge manually it's probably a gear/teleflex cable issue. You can disassemble these.

The cable is the thin tube in the left rear fenderwell behind the plastic cover. Is that tube kinked or bent with a sharp corner? A graceful sweeping curve should be okay.

Oddball question: there's nothing unusual like "the PO had a leak so he put RTV sealant on it and glued it shut..." is there?