Boy they sure did sugar coat that one. I wish that they’d be blunt and just say that any kind of over charge or even normal charge of a Li-ion pack (with just one bad cell) or a partial or direct short circuit can make a cell get hot! As soon as it gets to about 250°F it goes RTE or Runaway Thermal Event. That means it spontaneously ignites into a pretty pink flame thats hot enough to melt glass and water just makes it hotter. All can be done is to let it burn out.
Do you leave your laptop and cellphone outside?