I've found that humans are much better at doing than they are at thinking. Humans can generate countless hypotheses and evidence to support those hypotheses, and yet most human theories are flat out wrong. This is why we have the scientific method, which verifies hypothesis with good old fashioned elbow grease.
The real "five whys" question here is: "Why did this battery get through Boeing's (most certainly exhaustive) certification process and win FAA approval?" Boeing is well aware of the risks of lithium ion batteries and must have "proven" to themselves and the FAA that this design was sound through rigorous testing.
I suspect there is an "unknown unknown" here; something so unexpected a test couldn't be fathomed to exercise it. How does one find unknown unknowns? It's a fascinating question.
The real "five whys" question here is: "Why did this battery get through Boeing's (most certainly exhaustive) certification process and win FAA approval?" Boeing is well aware of the risks of lithium ion batteries and must have "proven" to themselves and the FAA that this design was sound through rigorous testing.
I suspect there is an "unknown unknown" here; something so unexpected a test couldn't be fathomed to exercise it. How does one find unknown unknowns? It's a fascinating question.