I have a Gardtec CP8L system that I inherited when I moved into my home several years ago. I wasn't left a code so asked the company who had serviced the system a couple of months previously to reset the system. On visiting, I was told that the system was faulty and the technician was unable to repair it. He left it powered-up such that the PIRs and bell box LEDs still flashed, so still acting as a deterrent. The keypad LCD display is blank. I have not touched the system, not even turning-off the mains, in case the external bell activates and I have no way of deactivating it. Is it possible that the anti-tamper mechanisms are still working? If so, how would I deactivate the external bell if it activates when removing the main unit cover?