Breakup sequence
I start it backwards.
Forward part fell to ground tail first upside down. That is due to aerodynamics and gravity center.
Before ground impact there was a fire underside between wings. Left underside up to the nose is sooted.
Left Engines probably ingested hot gasses from fire during falling phase. Main fan is sooted and scorched. Engine shows over heating damage.
These facts we know for sure.
Plane breakup last phases were abrupt with tail separation. There is very large piece of fuselage of right side. Almost from wings to tail. That one was last to break off. It could be that tail was last piece to break off from rear fuselage. At near cruising speed. That would explain strange hs and vs damage. Somewhat.
there was fire. First insid rear part that scorched seats and bodies.
could be it started from act tank installed on the plane. It was probably almost empty. But that is not sure.
fire started close to initial event.
Here i stop speculation.