Overloaded Li-Ion batteries don’t reliably explode. I would have expected them to place the explosive inside an oversized battery pouch along with a heating element in series with the battery. A microcontroller on the board could go short-circuit upon receiving a certain message, making a large current flow through the heating element and triggering the explosive.
Call them Li-Ion batteries to prevent confusion with lithium batteries such as CR-2032, which probably have been used in pagers.