Because the default code 1 2 3 4 not working again, but 1 0 2 0 can set it armed/disarmed.
When I want to change it again it doesn't work any more, as "1 0 2 0 then 1+3 together" it beeps differently, I've called a technician to came and check, but he can't solve it without the programming manual.
could someone help me to solve this problem? Or how to set it back to factory setting?
Thanks very much