One of mine did the deathbead GLOD thing, where it would work sometimes and then degrade, before finally not cooperating at all. A new power board cured that problem. I figured that it was the power board because I compared voltage readings between good and flaky boards and found noticeable differences, something that a simple PMU reset wouldn't fix.

Now if only someone would come forward with a schematic for the power board, I would be really happy, as I could fix the dead ones I have without having to totally replace them.