I just had the same problem this morning... dead 2015 Focus with zero power. I didn't have time to plug it in to see if that wakes it up, just climbed into the gas car to get myself to work. I had fully charged two days ago at a Charge Point pedestal, drove it a bit that evening but still had about 60miles range left that night. I didn't drive it at all yesterday.
Will the J1772 power connection change the 12v battery too or is the 12v battery part of the driven regeneration process?
Do you think the J1772 power will wake it up?
Is there a screen or part of the display where I can monitor the 12v battery status?
I did read in this post that it might take a "jump start" from another car... I haven't read that section in the manual yet, but expect there are instructions on how to do this in it? Yes, I have the mechanical key and can get to the manual.