1996 Pontiac Bonneville Car won't start, tried nearly every

So here's what I've got. My brother's '96 Bonneville was working perfectly fine a few days ago. Put it in park, turned it off, went into the house for the night, came out the next morning, and it wouldn't start. Dad's tried everything he can think of, short of pulling every single fuse and whatever to find a short.

When we turn the key into the Run position, something pulls all the power from the battery. It's not the starter (we've tried 3 different starters) and it's not the solenoid (pulled that, used a tester, definately not it). There's no sound or spark when we try to turn the key, but the car did make those dinging noises when you open the door and stuff. It just won't start. We know there's a short somewhere, there was the smell of rotting eggs. Dad thinks it might be a burned wire causing a short, but we can't think of where it could be. It's gotta be somewhere in the Run circuit.

Is there any way to figure this thing out without pulling every single fuse and whatchamakallit and testing for the short, or are we gonna be stuck fiddling with it for another weekend?

(If you've had the same problem and know exactly what I'm talking about and how to fix it, please send me an email asap.)