Fire would be consistant with that picture that was floating around the net.
New possible scenerio :
So plane catches fire but somehow one of the pilots survived but without having all the technical equipment needed to find where they were going and kept flipping switches trying to get help. .... Don’t believe it!
OK not this particular plane; the zigzag flight pattern of this plane says somebody was dodging...
plus the turn-off of the transponders and other system needing someone knowledgeable .....