replaced siren , now it won't shut off

Hornet 740t alarm 2005 Nissan Frontier (514N siren) The siren on my father's truck died so I replaced the it with a directed 514N. I reconnected the negative terminal on the battery and as expected the alarm went off. I hit the unlock button on the remote in hopes to shut it off but the siren continued to go off in it's "soft" mode (not it's loudest setting). I tried the valet button with no success although with the siren still going off I was still able to start the truck. So at this point I've pulled the fuse out of the alarm for some piece and quiet! Has anyone run into this problem before? Should I cut the black wire on the siren to eliminate the "soft chirp"? Or is the siren defective? All & any input is appreciated! Dave

Check the ground on the alarm brain.

Checked the ground under the dashboard and it's good. One thing that I just noticed this morning, there's no hood pin under the hood but the hood pin wire is in the engine bay. He was in an accident in August and the body shop replaced some of the front end and disconnected the hood pin and never reinstalled it. The wire and connector are taped so it's not making contact with any bare metal. Could this be the cause?