I haven't driven my car much this year. A few weeks back, the passenger window didn't go up or down except after trying it a few times. Then it worked fine. Flash forward to two days ago and the window wouldn't respond to anything that the switch was telling it to do. It wouldn't roll up and a rain storm was coming in.

I first suspected the switch was going bad, so I took it out and cleaned all of the connections. It was a bit dirty, but not bad. The switches are new as of a few years ago. Cleaning it didn't fix anything. I then swapped switches with the driver's side. The switch worked to control the driver's side, but the passenger side still didn't work. So the problem does not appear to be with the switches.

I took off just the upper door panel to see if anything looked suspicious, like a loose connection. I unplugged and reseated all of the molex-looking connections, but nothing changed. I did notice one of the connections in the middle of the door appeared to have burn marks, but I don't know what this connection controls:
2013-09-03 18.55.32.jpg

The connection with the burn marks is in the middle. Below is a closer picture of the connection in question.
2013-09-03 18.56.20.jpg

Looking through the parts history of the car, I don't see anything window related being replaced expect the switches and the window seal. If the window motors have been replaced, it would have been done by an owner prior to 2006.

What is the best next step in troubleshooting this?