The article fails to mention that Standing Rock is currently a very cold place. From what I can tell, it's been below freezing for weeks now.
In those conditions, batteries can drain much faster, report capacity incorrectly and then fail unexpectedly. It's probably magnified by all the extra work the radio has to do to find and hold a signal from the overloaded rural cell towers.
And anyone who's used a phone in extreme cold with gloves on knows that touchscreens can do a lot of weird things, including opening apps unexpectedly.
My hunch is that a large part of the reports are hearsay by visiting protestors who aren't used to the conditions.
https://en.wikipedia.org/wiki/Windows_SideShow
http://www.laptopmag.com/articles/intel-second-screen