I don't know if this issue has been floated yet, so forgive me if I missed it.
We'll know soon enough from the recording when it's released, but I'm wondering if a contributing factor might have been a native language difference between the Captain trying to deal with the avionics, and the FO flying the plane while everything was starting to go pear shaped.
If the Captain was about to do something in altering the flight computer controls, was he able to communicate that clearly to the pilot who had his hand on the stick? Factor in all the usual difficulties and stress in turbulence, unusual attitude, G-force, etc.
This may not have anything to do with what happened, but with two pilots from dissimilar native language backgrounds, I think it's worth considering.