Highly unlikely it's grounds if you were driving the car and this happened randomly, first check relays and fuses as I would give that advice for anything, then if it fell flat and now won't start it's likely a timing issue either mechanical or electrical. Start at your cas, I can think of a few times people have had one bolt holding in their cas they left hand tight from adjusting timing which wiggled out with vibrations. You have to realize just because you don't have any codes doesn't mean everything is operating correctly, it just means it thinks it is running correctly. If it's not a cas problem my next guess would be it's a bad ecu, take the cover off and check out all the capacitors. Normally I wouldn't waste my time with this to be honest lol.