Like you, I suffer Attention Surplus Disorder. The question that occurs to me is straightforward. These accidents occur when shipping “dead” batteries, IIRC. Maybe a chemist Freeper can help out here but I don’t get how a “charged” battery can be safe but a “dead” battery is dangerous. I suspect the problem is that the requisite care is taken of shipping “good” batteries and that disposing of “dead” batteries is likely to be attended with less vigilance.
As I understand it, it is not a matter of charged vs discharged; it is a matter of “spanking new” vs “old and beat up”. Let’s recognize first that a “discharged” batt can have charge left in it but not have enough to power what it was intended to power; or, it’s being discarded because it won;t accept enough charge for the user to want to keep using it. Second, there is high power density. Third, when these batts are older and abused, there can be punctures in the membranes separating the electrodes > short circuit > VERY reactive metal > lots of batts packed together. Fourth, WHEN they have an internal damage issue, they are subject to thermal runaway and the great place to have this go on is an overheated railroad car in Houston?
Dead batteries are not dead. They often just cant deliver the voltage they are supposed to.
Usually a cell or two, out of many, fail, and the battery cant deliver enough voltage to power a device. But the unaffected cells usually still have a lot of energy in them, ajd if there is corrosion inside the battery container, shorts can occur and thats where you get the fire risks. Because they will release their energy real quick then.