Can't start after new battery

Hi,

I'm trying to install a new battery on my 1996 Nissan Maxima. I hook up the positive terminal (red) first, and then the negative (black). The horn immediately starts beeping (horn, not alarm), and I can't start the car. It won't turn over, the horn continues to beep, and the car still won't start.

I killed the old battery by keeping the lights on, and I did the exact same thing last year, and replaced the battery and everything worked fine.

Any help is appreciated.

Thanks,

-Vic