2000 Chevy Cavalier (Automatic Transmission )

What works on mine, that I found on the internet, is to leave the key in the position one short of the position it reaches to actually try and start the car for 10 minutes. At that point the anti theft will stop blinking, and thr car can be started. I now use one key for the ignition, lock the car,go do something else for 10 minutes, and use a second key to get back into the car.