edit: after 20 comments, i’m adding a post description here, since most of the commenters so far appear not to be reading the article:
This is about how surprisingly cheap it is (eg $15,000) to buy a complete production line to be able to manufacture batteries with a layer of nearly-undetectable explosives inside of them, which can be triggered by off-the-shelf devices with only their firmware modified.
Heads up, I don’t think C4 explodes when burned. I think it requires electronic detonation or a blasting cap.
It’s right next to or in a high intensity lithium fire, not just a normal little flame. That should alter the equation somewhat.