As it turns out the Beaglebone Black has no protection circuitry between the USB plug and the board. While using a powered USB hub I had both a 12V and 5V cable sitting next to each other. I accidentally grabbed the wrong one and, well, now I'm down a BBB.
I was curious if it would be possible to find the exact component that died and replace it? Well of course it's "possible", but is it realistic? If so any tips on where I should start looking? Nothing on the board is visually damaged and there was no smoke. When I plugged in the adapter it just stopped, and of course didn't start up again.
Thanks in advance.