Nice work!

I had a board like that with intermittent 0 and not 0 asic. 

So if the chips have core vcc (which they do, your number is right) but they don't talk, what's next?

They need IO vcc, they need clock, and they need an unbroken connection to rx and tx on the header.

And they need to be alive, but since they came up once it's likely they are, and are just suffering an intermittent issue with one of the other items.

How good's your scope?