Perhaps the sub has an internal fuse to the amp section, though your description leads me to believe that it's not that simple. If it's under warranty, I wouldn't open it up. If it is under warranty, call B&W and have them give you directions for servicing.

Dude, you are on a college campus! Drop by the Electrical Engineering geek department and see if anybody wants to mess with it. Somebody would likely be able to measure the devices and see what the problem is.

If it makes you feel any better, most of us have trashed a component or twelve.