The window switch changes the polarity to the motor. Because the motor works in one direction and not the other, the motor is fine. It is one of the two switches. You do not need to take off the door panel.

Get a flat screwdriver and carefully pry up the rear window switches, both of them. Then plug the rear passenger side switch into the harness for the rear driver side and see if you get the same result. If the window now works, then it is the simple matter of getting a new passenger switch.

If the window still doesn't work, the fault is with the driver's master switch. This is probably what is wrong anyway, just more expensive to replace. And, why I suggested to move the switch up and down a bizzilion times to help clean up the internals.

The master switch can be 'cleaned', if you are lucky. Or it can be made totally infunctional if the cleaner doesn't work. You could look around on line for a new master switch, and there are a few people who refurbish the master switch.
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My back feels better when I sit in a Volvo seat