Starter Relay/Battery issue

[xXTallestXx]

Checked around the forums a bit before deciding to post this up, can't say I found anything like this.
06 Uly won't start, won't even give a *click* from trying to fire up, like it won't engage the starter at all. When I turn the key on, the lights won't even come on, but if I hook up a battery/jump start, it'll work and keep charge, but only for a minute. With the seat off and key on, I get a buzzing sound coming directly from the fuse box, the buzzing stops when I take out the starter relay. If I replace the relay with a new one, the same buzzing occurs. The read I'm getting from my multimeter is less than 12v and dropping (first 10.5, now 9.6). Should I just get a new fuse box, or could this be a short? Is it too difficult to fix the fuse box?