My neighbour's home was burgled and the Nexus 8 alarm, which I fitted years ago, activated. Burglars smashed the external bell unit and cut the cable but control panel situated in the attic continued to sound so they left empty handed. However having replaced the damaged Nexus bell box with a propriatory HKC SABB external bell box / siren and reprogramming using Engineers Code handbook - BT continued to display. I then bought a used but tested control panel motherboard (in case the fault had damaged the tamper circuitry) no change. Cable replaced and continuity tested. At wits end... can you assist. Many thanks Dennis (retired telecommunications technician).

Denis, December 2016

Also read the manual with the new bellbox and make sure it is wired up correctly the tamper can be confusing to some.

R, December 2016

Is it a bungalow? Bellboxes should be installed high out of reach. I highly suspect a 12v fuse has blown in the panel which will need replaced. The burglars would have caused a short circuit when they cut the cable.

R, December 2016