Try replacing the LED first. You can source ultra-bright blues/whites/reds (whatever you're after) from Jaycar Electronics. If its too bright, current limit it with a resistor.
I would imagine the LED is not driven straight off the microprocessor inside the AVS alarm unit, but rather switched through a transistor. Can't say for sure (have never opened an AVS box up before), but if this is the case you may need to have this part replaced. That's probably an AVS return to manufacturer job I would imagine - as touching the internals would most likely void your warranty.
But try the striaght LED replace first off - that might hopefully do the trick.
Yeah I've actually checked and there is no voltage coming out of the unit to the LED. Used one of those multi meter devices. So I'm assuming it's something internal.