Dan Pearce

Hi I have just bought an apartment following a death, the alarm system is currently disabled in the fuse box as the vendors family were not aware of the code for the alarm, I have tried to use the factory default code to reset the alarm but this has evidently been unsuccesful, can anyone advise how I can get the system back to the factory defaults given as soon as I turn it on all the alarms sound and all the panel indicators go red?