Taking apart the RRT-2:
1) remove the bezel ring, lens, O-ring, reflector, and black lens centering ring from the front of the light.
2) desolder the two wires from the MCPCB and remove the MCPCB from the light.
3) unscrew the aluminum heatsink and remove it.
4) unscrew the two small screws holding the driver board from the body.
This is as far as I've gotten with mine. I was unable to loosen the two halves of the head that retains the selector ring. The driver board is attached to the lower part of the head the selector ring is indexed on the upper. If they go out of sync then it'll not work right.
tbarb169, rotating a small magnet around the selector ring didn't turn on the light? It almost sounds like your head's upper part and the lower part are out of sync by 160+ degrees and the magnet is not getting near enough to the hall sensors to turn the light on. To locate the magnet, rotate the ring until the arrow points at "High" and the magnet will be located under the scallop sitting over "Standby". At least that's where I found mine.