Hi.
I bought BBB Rev.c 2 month ago.
Two device is problem with power.
I used 5v DC USB power to BBB.
Nothing connected sensors, Nothing run programs, only POWER UP.
But, My BBB powered down a few hours or day,
And, I didn't use to my BBB.
5v DC USB Power used BBB is Computer USB Port with BBB, smartphone chager with another BBB.