Press *8-1500 or *8-1550 on the keypad to enter programming mode. If the system does not beep, the panel needs a hard reset to clear all of the previously programmed codes.
Disconnect all power to do a hard reset of the system. This will reset all of the previously programmed codes, including the master code.
Leave all of the power disconnected for at least ten seconds.
Turn the power back on after 10 seconds. Once the system has been reset, all of the default values will be restored. The master code will also be reset to 1234.
Press 1234 and enter. This will allow you to enter the programming mode under the reset master installer code. Once you have done this, you may reprogram the codes as necessary.