Hello & Welcome,
Is the Security indicator turning on when you try to start the vehicle?
Can you tell me if this an after-market alarm, or the factory installed alarm. The factory alarm should just honk the horn.
I don't think that the factory alarm has a siren, just the horn.
When you hook up the battery, did you connect the negative terminal last?
I would at least give that a try.
You might also want to try this: Disconnect BOTH terminals from the battery and then touch those two cables together a few times. This should "discharge" anything that might be holding a charge in the electrical system.
Then reconnect the positive first, then the negative.
I also have a procedure for "relearning" the security code for the system, but you may have to suffer through the alarm until it resets. But most alarms stop after a minute or two. I am just not finding a siren of any kind on the factory alarm system, just the horn.
Let me know what happens with the Negative terminal last.