Met a friend of a friend some months ago who customised electrical vehicles of all kinds, a battery like this blew up while he and his best friend were close to it. His friend died and he got burned real bad, the left side of his body is badly scarred and he lost fingers, hearing, most of his vision and other stuff on that side.
We sat and talked for most of the night and after that I have a whole new "respect" for batteries. My mom uses an e-bike daily and I've made real sure she is aware of the possible danger. She used to store and charge the battery close to the door of her apartment, now it's in a battery safety bag in one of the closets where it wouldn't be in the way of getting out if something happens.
Fucking scary stuff.