Alarm won't turn off

My battery was low enough that I could not start the car so the alarm went off. After several attempts at starting the car it finally locked it from starting at all. Well, I charged the battery, got in the car (the alarm went off). I waited for the alarm to stop alarming and started the car.

It did start, but the alarm still went off. And even though it is started it continues to go off every time I open the door or start the car. Which drains the battery making so it won't start next time (if not running).

So what I ended up doing was when getting out I wind down the window open the door get out, close the door, wait for the alarm to stop going off and then reach in and turn off the car. Not very convient. And very amusing to people watching LOL.

Before this, the way to get the alarm to go off was to start the car. Now I don't know how to get it to turn off.

Don't you have a remote ?

Could it be that one of the door switches is not working right....I took mine off and cleaned them when I got the vehicle. Are your door lights staying on if you have them?
Isuzus are known for their electrical gremlins. An undercharged battery or failing alternator are chronic causes of problems. Any codes stored in your ECM?
One guys opinion.