It really sounds mechanical vs. electric.

You should remove the door panel so as to give it a full inspection. I really don't think you have a way around this. Look for phillip screws holding the door panel. Can't remember if there was two or just one. One for sure on the inner door handle. After removing the screws, and the window molding piece, then carefully "pop off" the panel.

You may have to cut/taer through that plastic sound wrap stuff (so as to access the problem)---- just replace it later.