I think I have found what causes these things to die. I don't want to say what until I've confirmed it. But if I'm right, and I can resurrect one that's died, I'll happily show everyone what to do.
I would much prefer a dead one that is NOT potted. To work with a potted one I'll have to cut the two boards apart with a hacksaw. I'll still be able to dig through the potting and check the possible trouble spot, but it's unlikely I would be able to try the fix and then see if it works afterwards. It also needs to be complete and in the state it was right after removal with no parts scavenged.
If you donate an un-potted & unmolested dead driver and I manage to fix it, I'll return it to you and you will not only have a working driver again, but also know you helped other people avoid the aggravation of these things burning up at $20 a pop.
Doesn't matter if it's the 5/7/9 LED version or 3 mode/5 mode. If it's a KD/LCK-LED/Lightmalls 'beast driver' and it's dead, I want it.