If its been off for some time it has probarbly reset itself to factory settings. You need a manual really to set back up. Try 0123, 1234, 5678, 7890. These are the most common factory set codes. Generlaaly when you put a panel on in its factory defaults you have to put the code in straight away to get to day mode. You will get a manual from e-bay on CD for a few quid.
Tony T, February 2010