I've had this exact issue before. This happened to a stock board of mine after I dropped a piece of metal on the regs. If you hold the power button down does it go tick-tick-tick-tick-tick? If so, I would assume that the board itself is fine but the regs are screwed. The regs are pretty sensitive, complicated, and not well documented, so there isn't much you can do.
I'm pretty sure your board should be able to still work off of custom regulators.