2001 Dodge Neon factory alarm

It sounds like whoever had this car before you took it to their dealer and had the factory alarm activated. The trunk popping means that when the dealer activated the alarm, they used the body code of a PT cruiser instead of a Neon. It is possible that their mistake can not be undone without a new Keyless Entry module. Your dealer has the only tool (DRB-III Scan Tool) available for making changes to this area of your car. This is not anything you can do yourself. There is no wire you can cut to deactivate the alarm. You could, however, cut the wire to the trunk release.