Scantronic 9448 - I want to turn mains off?

Hi - seems a strange question but one of my sockets is not child-proof, resulting in my broadband and computer equipment being turned on/off 10 times per day. I want to change the socket for a safer one but when I isolate the mains, the power to the control panel goes and the external alarm goes off. I cannot then stop it until I restore power.
I have the codes etc and want to know if there's anyway of taking it off 'day' setting so I can do the work on the socket in safety.
I believe I can also disconnect the battery in the external box (do tell me if this is not so) but would rather not have the hassle of this if I can sort it out at the box.
The wierd thing is that I've doen work on the electrics downstairs before, including rewiring the ring the control panel is on, without any problems of this sort so can't work out why it's a problem now.
Help gratefully appreciated.