Texecom Veritas 8 alarm panel locked out?

We recently installed some new lights and had to switch off the mains to do so, afterwards the main panel on the alarm has become frozen/locked out. The tamper, unset, power lights and zones 3/5/7 are lit (we only have zones 1-3 in use). When we enter our user code there are no tones from the key pad and nothing has changed. Have seen other people mention the '4321' code with the mains disconnected but would appreciate some assistance in case this problem has a different resolution.

March 2008