This is a longshot, but worth a try.....
I was in the process of saving settings to my CC3D board after changing a few PIDs and the board disconnect from the PC all of a sudden, without warning. I unplugged and plugged back in the USB cable and got nothing....no lights on the board at all. I try to power on with a battery and the same thing happens...no lights at all... I would assume the board decided to nuke itself and just quit? Nothing I can do about it is there?