why struggle to stop it. Its easy to stop you just press the unlock button on the remote.
Either sit in the middle of the back seat of the car or get a friend to do it, (If your by yourself put a window down so you can hear the siren better)
Lock the car with the remote as normal (one press of the lock button)
Time using your watch 2 minutes. (At least one minute before it arms fully)
Then while having one hand holding your remote ready to press the unlock button wave your other arm about in the air, this will trigger the ultrasonics and the alarm will sound.
Then just press the unlock button on your remote key to stop the alarm and unlock the doors.