accentag3 with ADE keypad tamper?

Hi I fitted this alarm 18 months ago at my brothers house,yesterday evening it detected a tamper which he stopped by entering his pin code.
The tamper light is now lit on the keypad and it will not re set,my main concern is that when we put the alarm in we used the existing wiring rather than running new which came with the kit.
Is there a possibility that the wiring has perished in some way?.
The exterior bell-strobe has also lost normal function and instead of alternating twin green leds has ceased apart from the left one which is constantly flashing.
Replacing the wiring is too big a job for me and so I was wondering if there is a way I could track down or maybe replace that length?.
Your help suggestions are eagerly awaited and many thanx.