Help!!!!

I have a 2005 Trailblazer LS, V6, 4-door, 4WD.

I had the dealer to install an after-market alarm system , with kill switch and remote start.

My alarm is doing its own thing. I was parked at work and when I tried to start my truck it appeared that my battery had died. I tried to get my key out of the ignition but it would not release, it was locked in accessory mode. Once I got a jump the key did release. I turned truck off to verify that the key would not be locked in the ignition. It appears that it was no longer an issue. I restarted the truck, no problem BUT, the alarm started to go off. I tried using the remote to disengage it but the alarm continued. I kept hitting the unlock and lock buttons and it stopped but, as soon as I touched the brake to back out, the alarm began again and the interior lights began to flash continuously. I again started to push the remote buttons and the alarm stopped for a moment. I drove home with the alarm still engaged, sounding off every few hundred feet and interior lights flashing. Any time I had to touch brakes for turns, the alarm went into full theft mode but,did not cut car off. When I parked at home, of course the alarm was sounding off in theft mode. I tried to engage valet mode, to no avail. I raised the hood to figure out if there was some way to disengage and I could not figure it out. What I noticed was that when the hood was completely closed the alarm began again and so I figured to not let the hood completely down when the alarm stopped. Prior to last night and as I drove to work, there were no signs of trouble with my alarm.

Will someone PLEASE, tell me what's going on? I think my baby has lost its mind!! I know nothing about the mechanics of a car. I will have to take to a mechanic however, I would atleast like to kinda know what he's talking about.

HELP!!! Thanks!!