Theft alarm

We have been having problems with our Chrysler New Yorker. To set the alarm you hit the automatic lock button before you you get out of the car. Its caused a lot of headaches and so we don’t set it anymore however my father-in-law moved the car and set the alarm. If the alarm is set when you unlock it with the key on the driver side door the alarm sounds. normally when this happend we could go through the passenger side door to disarm it. This time it didn’t work and the alarm kept sounding. we tried unlocking the trunk, disconecting the battery, grounding out the system to get rid of any current, we tried starting the car with the key and it starts for a few seconds and kills. We heard if you start the car and turn it off 20 times it will shut off the alarm. please help me get this car running I’m sick of letting my wife use my truck.