Thanks for this info and thread, but sorry you had the difficulty. I have a 2013 Focus BEV since September 2012. I had just mentioned to some people that the only maintenance expense the car has had was a new set of tires a year ago at 60000 miles.
I was just going to drive to the grocery store and the car was completely dead. I took off the red lead on the battery and retightened, but nothing. I was going to check fuses but jumped inside on the computer and found this thread in about 30 seconds. I jumped from my 2003 Saturn Vue, without it running, to the positive battery terminal and a nut on the frame and immediately heard some clicking. The dashboard came to life when I pushed the start button and it looked alive. It looks like it needs to reset some things including the clock.
As every night since I've owned it, it was connected to the 220V charger. The battery is seven years old and the temperature was in the mid-30s last night, so I guess I'm due!
I have a dental appointment early in the morning so will check early if it starts, I have a 13.8VDC power supply I can use if necessary to charge or jump the battery, or will use and take the Saturn battery with me with jumper cables if needed to get a new battery.
I was taken aback at first but honestly these are the only incidents of non-functioning I've had with the Focus BEV in seven years and a month. I can't complain.
Thanks for the great info here.