What we now know, is that the fire containment and and ventilation processes protect the 787. We also know that a battery melt down still remains a problem. So what Boeing learned since this last incident with Japan Airlines. Several things, the battery melted down with voltage controls in place. If the voltage controls worked as expected then it points to the battery core and construction itself. The battery was fully protected from every possible battery failure problem known at the time, except itself. Boeing is now looking at battery x-rays for the determination of inherent flaws. Boeing's robust treatment of battery habitat has narrowed the battery flaw to internals that pass by into Japan Airline 787 operations and onto the maintenance segment.
That can be said about the battery from an outside looking perspective. The battery has a problem and it starts within the battery under limited influence from the airplane itself. Voltage regulation keeps the battery's electrical inputs constant and protected from electrical surges and anomalies, thus not damaging the battery core. Electrical out flows are regulated and do not require a tasking battery surge for keeping up with instantaneous equipment start-ups. The battery is protected after the fact of battery damage and thermal runaway. Additional damage is stopped under operation once its starts smoking. The problem is isolated and contained.
So if all the battery protection works and contains thermal runaway it leaves a very big target on those factory x-rays on the battery before it leaves for Boeing. An airline gets a crack in its windshield. It gets replaced. An easy solution preventing windsield implosion during flight. A battery has a crack at the molecular level no one cares until the battery containment system is called upon. Boeing will now have an easier time of identifying what is the causal problem of the battery.
Find a battery on the loading dock side of the battery factory with those cracks in its storage substrate, and test the battery until it breaks. Then you may find the causal problem for JAL's resting aircraft. Multiple short flight cycles may stress the battery performance with multiple landings and take-offs each day, then followed by a long route. These are questions that may make JAL operations unique. What happens to the battery exposure during a variety of operations and then rest? Are those battery "cracks" exposed and made over wrought with continuos service and then a runaway breakouts while at rest?
What is queried here there are now more questions, and less answers than before. Boeing, can possibly save the day on this venture, by getting its arms around the cause not the treatment. The treatment does not stop a battery runaway from starting, it just stops it like a Herpes virus. A bad virus still starts up in the containment area. Boeing needs a cure for that battery design and its assumptions. I hope that x-rays finds the culprit even at the molecular level. It makes the problem a lot smaller.