Come on everybody, let’s use Occam’s Razor on this—This simplest solution is probably correct. This was probably caused by a single point of failure. No need for convoluted conspiracy/crazy pilot suicide missions.
I suggest that could be the Crew Oxygen Bottle. Most Airliners have this vulnerability. It would cause massive electrical issues, decompression, and now from the latest report the autopilot is OFF, the aircraft was left meandering. It’s really not that difficult if you know how the avionics bay is constructed and how a disabled B777 once trimmed for cruise could fly on to fuel exhaustion.