2005 Other Chevrolet Models not sure if right category but m

Electrical problem
2005 Other Chevrolet Models Automatic

My anti theft alarm keeps going off. I have 2005 chevy classic. I thought I accidentally hit the button but 15 minutes later it turned back on. I shut it off while I looked for help but it turned on again I shut it off. And found out that every mechanic is closed. And now the alarm will not shut off at all. I turned the car on and the alarm will stop but soon as I turn it off it continues. So I now have my car running until it shuts off.