So I talked to someone who suggested my battery might be dead and that I try charging it, but as "Bullmtnbiker" mentions, the horn blasted as soon as I connected the negative terminal of the battery to charge. Finally, I just tried connecting it and running into the vehicle to start it, and that stopped the horn blasts immediately and it started and ran fine. I just hooked up to a trickle charge overnight to get the wounded battery back in shape.