Accenta 6 Alarm System Not Responding?

Hi

We have recently moved into a house that has this alarm system. The previous owners left the user manual and told us the code which I've since changed to our own code. All was working ok until the weekend. We are decorating our kitchen, which is at the opposite end of the house from where the control panel is situated. There is an exit door from the kitchen out of the house. Next to the exit door is an old looking silver box that has a key. The box measures about 3 inch by 3 inch by an inch dpth. The top of the box is open (you can see inside), and isdie you can see a piese of what looks like wood. Turning the key just seems to move this piece of wood up and down. There didnt seem to be any connections to this box, it seemed to be free standing and so because I didnt know what it was for and because its unsightly I decided to remove it, but when I tried to it set the alarm system going. Quickly I rused to the front, and turned it off by entering my code but now the control panel is dead, it has the green led day illuminated, and the red power, and also the red 'attack'. I've tried to reset it but it's dead, no button seems to work. Does anyone have any ideas how I get it to work again? And also, whats the box in the kitchen do? It's such an amateur looking bit of tin and wood that I thought it didnt do anything but obviosly it does - help!! Could someone e-mail me at andie.lambourne@bt.com, thanks in advance for any help.