What happens to a plane if you go through a 100mph updraft, and then when you suddenly exit, your indicators go bonkers?
And you are totally on IFR.
This is why this new information is so puzzling. We have an aircraft, like all passenger aircraft, that is designed to return to straight and level flight. And, assuming this happened at altitude, 35K feet is more than enough real estate to regain control of the aircraft and resume level flight - assuming that the airplane was controllable and under power.
Also, a commercial airliner is not built to withstand the stress of a 30K foot (or more) flat spin. I can't imagine it not breaking apart, at least big parts of it, before it hit the water.
While the bottom to top crushing of the fuselage is an interesting and enlightening clue, it leaves many, many questions unanswered.
Are you supposing that the auto pilot countered the updraft, but when the updraft ended, the controls were lost so what appeared to be holding a steady course was really plunging to the ocean?