Modern 2.4GHz RC gear requires a significant level of tech-expertise to "hijack" in the manner suggested.
Occam's Razor has the answer...
Simple mechanical, electrical or operator failure -- nothing more, nothing less.
Too many would-be "drone" operators have scant understanding of the need for a maintenance schedule and proper planning before deploying even the smallest and most lightweight of craft.
The problem is that far to many people buy these things and then treat them as if they'll just keep working forever -- simply charge the battery and fly!
Unfortunately, props fatigue, motor bearings wear, ESCs can overheat and flight controllers can fail.
There's a hell of a lot more to safely deploying one of these craft than flipping a few switches and wiggling some sticks.
I'm not a commercial operator -- I fly for fun but even *I* am very much aware of the importance of good housekeeping and planning when it comes to using these things safely.