Comment by numpad0

The pagers in question is believed to be a dry cell operated model. It could be a rigged AA battery.

...oh no. They must have handed out those USB rechargeable batteries as an upgrade. The bad guys want to be able to charge it, so they would be incentivized to align the charge port with case back and explosives facing the user. Then the battery could be triggered by time since synchronization && backlight current draw && button press beep.