This panel is held by what mechanics call "Christmas Tree" fasteners. Trouble with the Montana (or the Venture) is they have turned out to be "one time use' that is they don't hold good when re-used, get about 15 new ones befofe you start.
Get the window switch out of the armrest first. The image is not perfect in my mind but there is almost always screws holding the panel at the arm rest (look underneath). Now I may just be a dumb a**, but I always found going deeper into the window "innards" much more difficult than lets say a full size GM pickup. The window "guts' are in a some what modular setup. It's trying, and things must be massaged to fit well, not my favorite motor and regualtor to do. I have done about 30 of them,pretty common.
Really make sure it's not the switch, first.