Why is my 98 honda accord doing this?

Twice I have heard it making a loud sound similar to a car horn but it doesn't sound like my horn. The car wasn't running when it was making this noise as a matter of fact it hadnt been driven in 2 days. The first time it did it, it stopped on its own but the second time I had to disconnect the battery as I could not get it to stop. The sound continued even after I started the car. Now I reconnected the battery and everything works but the car won't start. Can someone please tell me what is going on.

Your oscillation adjustment relay screw is probably out of whack. Have someone that knows about them adjust it for you.

It's related to the after market alarm system the car has. Look at the FCC# on the back of the remote and I'll tell you how to correct the problem.