Step 1:
Remove one battery of control panel, wait 5 minutes
Step 2:
Press and hold "up arrow" button and insert battery, “ENTER CODE” will appear
Step 3
Release "up arrow" button and press "KEY" button ("quick" on HA2000T)
Step 4
System will reset all code and the alarm will be armed
Step 5
Press 0000 and "OK" button to disarm system