Tomos

H there, I'm an electrician, I recently disconnected a Citadel intruder alarm as part of a rewire. During the time that the alarm was disconnected, the battery died. Now whenever I re-insert the fuse (fused connection, not internal) the alarm sounds, and the code no longer works. Has the alarm factory reset, or can I do so? Is it a case of installing/recharging the battery first? Is there a maintenance function? What is my best course of action (preferably without calling another company, I'd prefer to learn) I can's seem to find an instruction manual anywhere online, and there is no model number on any of the control units. Thanks, Tomos