Does anyone know how to unhook the power cable on the front door. Seems to be a plastic clip

There are four cables in the door on my 05 S60, one by the mirror, two by the window controls and one gray one up high. All of them have a central tab you press in and pull down on the outside edges of the connector (not easy when you're holding the door by the handle in the other hand). If you have a short stool or box to rest the door panel on then it's short work but I've removed them all with one hand as well. Don't forget to remove the door release cable, just snaps out, and to snap it back in when you're ready to button everything up. The cable on the passenger side was disconnected when I bought the car, first thing I had to take care of.

Not familiar with the newer cars. The early 850 just pulled out of the "A" pillar. Later, there was a small torx screw holding it to the "A" pillar.

I would guess that the actual plug is behind the "A" pillar in the newer cars, as it was with the older cars. What you are looking at should be used to keep any water out.
--
Keeping it running is better than buying new