tMMt2 comments

@Probie

I thought these planes went through thousands of hours of tests before they fly? Nothing showed up??

You are right, they do, hundreds of hours, anyway. Thing with life tests, though, they tell you something still worked after 2000 hours. They don't tell you if it still works after 2001 hours (which is why you swap things out, after all) and they don't tell you if the test item was put together extra special carefully because it was the test item and not just thrown together on a Friday afternoon by someone in a hurry to get to the game.

As Crazedinjapan said, there's only been one publicly released incident report so far and that blamed the wiring in the aircraft, not the battery. The JAL fire and the ANA incident may or may not have the same root cause, we have to wait and see.

@Probie, it's not just Japan. United, Air India, Qatar and LAN have reported electrical problems and the launch was delayed after a fire in the electrical bay of one of the proving planes. United have reported the battery wiring was incorrect. Source nyc787.blogspot.jp.