1. No Maydays heard, doesn't mean they didn't try; radio com problems reported all over this zone (weather?) and radio problems with this particular aircraft.
2. or engine refight too late. The process is not easy, based on speed and altitude which will lack in the first place; need to troubleshoot many other problems at the same time; need to make distress call with unreliable radioset due to lack of main power.
3. NIL...no more ACARS in case of double engines flameout.
You can't push a theory unless you also consider the cons against the theory.
But just to keep the discussion alive, give a thought to what happens to the flight after the engines flame out and ACARS goes off line with nary a clue that the individual electrical generators preceeded it.