Help - won't start / rear fan

Wewent to start our 99 Suburban and it is dead - The odd part is that the rear fan (not AC or heat) is on and will not turn off. Eventhough the battery does not have enough juice to start the fan keeps going. I have the controls to the rear off. Any advice???????

Update - The fan seems to be the fan on the side in the rear cargo area. I removed the panel and disconnected the fan. After a jump everything starts fine. However, now that this motor on the floor in the cargo campartment is disconnected, the rear AC/Heat does not work. Sounds like a short - what do you think?