is this the factory alarm where the horn honks?
I think so. It is actually my son's car, I am not that familiar with it.
It is very loud.... I tried putting the key in the ignition to II and pressing buttons on the car key fob thing.
OK. if it is the factory alarm you need to have the hood open and the doors locked. When you hook up the battery cables and the horn starts unlock the drivers door with the key. If it is a siren type alarm try leaving the key in the "ON" position before you hook up the battery.
happy to help out.
One of those 2 methods should work for you.