Glad you are OK.
Yes, Lithium batteries can pack a punch and do deserve some consideration and caution. Granted there are some Lithium versions "safer" than others but the fact remains that for the size and weight, they hold a considerable amount of charge energy even when stored.
Folks have gotten used to these batteries and don't pay much respect to the stored energy in them..
Good chance your device malfunctioned (shorted) while being stored or the other possibility is it may have had one of the bad batches of Lithium batteries which had impurities which over time would short out the cells which were recalled.