No power to drivers door

The cylinder shaped object that you are referring to is probably a wiring duct. It should be plastic or rubbery and probably black. You can get down in there and pull it back and inspect the wires. If you see any fraying, then you know what your problem is. Frayed wiring there is pretty common among all cars. If you want, take a picture of it and post it to this site so we can be sure of what you are talking about.

Also, it would not be a bad idea to pull the switches out and check to make sure that the wires are tightly connected.