I've had a problem with my defender td5 recently, I was called out of work by security saying my alarm was going off. However there was only the horn sounding, unlocked and started but the horn stayed on!! But after starting went to a very low drone and ceased working all together, now the little red light flashes like mad and on starting the alarm gives a short burst and stops??? This is beyond anything I've encountered before but I've resorted to removing the fuse for alarm sounding. Any advice or help as this is a nightmare