Comment by CydeWeys

> So trigger some kind of process to cause the batteries to overheat

Where are you getting this part from? There's no evidence that the batteries were triggered to overheat; indeed doing so would be counter-productive, as it would cause the people holding the devices to know something is wrong and potentially move them farther away from their own body. The pagers exploded suddenly without warning. The only trigger/detonation involved was setting off the high explosive. The battery was uninvolved, only used to make the pager itself work.