'90 Pathfinder - no sound from radio and window sags (I'm no expert, need help)

[pickinandy]

The radio in my dad's Pathfinder stopped producing any sound some months ago. It has power (lights up when 'Power' button is pressed) but nothing comes through any of the speakers. I haven't pulled it out of the dash yet to check for loose connections. So far as I know, it's the factory radio.Also, does anyone know how to pull off the rear passenger door panel? The window motor doesn't do anything (we think it's disconnected since we can hear it turning whenever we push the button) and since the window slowly drops to an open position, we'd really like to get the panel off and tape or glue it closed so rain won't keep falling in.