That's why I suggest it was a "non-standard" battery and no one from the manufacturer. The problem is proving that, as the manufacturer will provide all sorts of tests to show their batteries are "safe" and that it must have been an "imported copy" as, well, when something lifts like that then there ain't going to be much left of the battery to confirm it wasn't an imported copy so, in reality, the manufacturer could count themselves as "safe" unless someone proves it was a genuine battery from the manufacturer.
Wouldn't go as far as a "thermobaric" explosion though, because what we are looking at is an uncontrolled release of energy in a confined space, I would class it more equivalent to a pipe bomb personally.