Good man your feedback can help others,
We use an ACT meter on the batteries and it tells us in seconds if a battery is kaput,if it's good we move on and troubleshoot by metering the system.
Unfortunately without the ACT your only option is to change the backup battery so you can rule it out and all spurious faults associated with a duff one.
Chances are it is a tamper on the system so do a few checks:
Ensure control panel lid is seated and secure,
Check all PIR's are secure and covers are seated and secure,
check the remote keypads (if fitted) for secure fixing and their covers are not loose and are correctly seated,
If all appears ok then I suggest you get a pro in who can meter the circuit's and isolate one tamper circuit at a time until he finds and corrects the fault.
Sorry we can't tell you how to defeat the tamper circuits on here,so I wish you all the best with it and good luck.
e manno
February 2013