Hi paul sorry for the delay.
I don't find you stupid and certainly not for expressing an interest in equipment that like you and many other users don't understand.
Firstly the sounder has it's own battery known as a SAB.
Changing the 1st or 2nd user code method and acceptance of the new isn't what you have described in your post,what you have done is simply reset the panel with the factory default code.
you can't enter into programming with the user code,for that you need the engineering code.
Just let it ring whilst you change the battery then refer to the user manual and change the code.Test the system,full part sets.
Try the factory default engineerin code.
See if you can get into engineering with it,if you can then check the programming then change the engineering code as well.
You could try all this yourself but I'd suggest you search the net for the book and read it or you could call a pro in .
Ps if you simply want to shut the system down until you get around to sorting it,then isolate mains &battery,then let the sounder sound until it's battery dies.
e manno
July 2013