Having said that, of course, safety mechanisms should have shut down everything before the temperature goes into the proximity of the danger zone.
Um, they did. It's literally the very first sentence of the article.
The guy decided to turn it back on, which is when it blew up.
Where is that power going to come from if not the battery? you can't have any logic without power.
I'll notice when I open my bag and find a hot laptop with little battery left.
Oh and burn marks in the screen. Lenovo has already replaced one screen.
To the point of a comment above, this is why the article is noticed when a MacBook is involved, but it wouldn't be if it was, say, a Dell. We just assume that this obviously shoddy piece of generic Windows crap could just catch fire due to design flaws. If my MacBook caught fire, I'd be shocked. If my Samsung Chromebook caught fire, I wouldn't be. If the dayjob Dell caught fire, I'd call it par for the course.
If it did indeed recognize the heat problem and turn itself off, they should likely either tell the user or not allow it to turn back on until it cools down.
I'm not sure this is what actually happened, anyway. He says it caught fire within a few seconds of being turned back on. Either the thermal protection is faulty (it should shut off before the battery gets anywhere near that point) or the machine shut off for some other reason (excessive CPU temperature, say).
Which is exactly what anyone else would do if their laptop suddenly shut off without giving any clear warning that the situation was dangerous. A proper safety system would need to notify the user of the possibility of a battery fire and advise them to take the laptop somewhere where fire damage would be minimized.
But it's not entirely clear to me that safety features were actually triggered. Perhaps the battery failed and the machine shut down due to lack of power or a power fluctuation. The fire could have been inevitable at that point, and his actions after the shutdown and before the fire are just red herrings.
I think this comes from a lack of understanding about how the problem started. Yes, excessive heat CAN cause a critical battery condition, but this seems unlikely, as the batteries should be designed to handle much more heat than the CPU can generate. Rather, I think the batteries caused the heat, not the other way around.
The firmware on my PC will detect that it is running too hot, and halt. Presumably it will halt to catch fire since it seems as though the only thermal management at that point are the fans, but that is another story.