UPDATE: I tried removing the battery, but the detector's still going -- as I suspected, the battery's just a backup. I would try replacing it with a new one, but I have no 9V batteries handy, so I just put the old one back in.
And yes, the detector is going full force, in earnest, only stopping to "catch its breath" for 10-20 second intervals before blasting forth again.
And yes, I have checked everywhere in my apartment, and there is no conceivable legitimate reason, fire or CO-related, that it should be going off. If it was the OMG SILENT KILLER, I'm pretty sure I'd be dead by this point, because we're past the half-hour mark now.
I'd go out to get a battery, but I have no car, I'm not sure how late the buses run, and most of the convenience stores/pharmacies within walking distance are probably closed by now (retarded this close to the college, I know)
As for smashing the damn thing...if I was paying the rent on my own dime, I think I could take any heat that would result from minor tampering with the fire equipment. But since it's my parents' dime, I naturally have to exercise a fair bit of prudence in whatever I do here.