2013 Ford C-Max Energi battery

Dear Car Talk,
Recently once in a while my car didn’t start and a message of “System off to save battery” appeared on screen. The manual says nothing about this situation and how to restart. I used a car jump starter to start the car. After the car started, I checked the battery and it always still had the same juice as when I turned it off. It wasn’t dead or drained.
My questions: what’s wrong with the car and how to start w/o using the car jump stater; what should I do to fix it?
Thank you.

Perhaps your test equipment is flawed, have the 12 volt battery tested by a professional, I suspect it is failing.