After many years of excellent service the keypad (Mk 1) became unreliable and so I changed it for the newer (Mk2) version, with larger buttons. The change went well until I took it out of engineering mode and since then the tamper light has been illuminated. I had tried to remove and replace the keyboard several times but still get the same result. Keys now "beep" and the alarm won't set, although I can return it to engineering mode. Any advice would be much appreciated. Thanks