im no rotor expert, but it sounds like theres a problem with the current from the batteries going to the board. i would call dye and ask what they think of it.
When you say it just turns off, does the board actually turn off, or does it just stop spinning even though the light is still on?
Well I PRESUME the board turns off because the light slowly dims until it goes off and it stops spinning. And I know it isn't a battery problem because I've used brand new batteries before.
Took your advice and called them, but not the answer I was expecting.
The guy said it was probably a board problem, possibly that it somehow got short circuited, and that I should buy a new board and replace it.