I thought they catch fire and burn down slowly.
Correct. Both the recent pager and radio attacks, and the 1996 cell phone attack, were performed by planting military explosives inside the devices in advance.
There is no magical way to hack the electronics to make a lithium battery straight up explode.
The US has a few thousand miles of land borders, and there are some neat places to visit along them.
I’m not at all sure where this gentleman went or why.