Rear window stop working

It sounds as if the window motor itself is jammed, if the lights are dimming that signifies the switch is doing its job. I'd remove the rear door panel and examine the window motor and crank system. If rusted, your best bet it to remove the crank and motor to clean them of rust. I personally used a garage door lubricant for my window crank, but any kind of grease should do the trick after cleaning. Maybe check out the window seals as well, if it is rust.