Possible chain of events
So...to elaborate on AAKEE:s earlier summary:
1) A/P disconnect (due to incorrect pitch indication from IRU?).
2) PF pushes nose down 1s later (due to incorrect pitch indication on PFD?).
3) g loading and AOA follows.
4) PF pushes nose down multiple times in coming seconds.
5) Stab trim increases towards nose down pitch.
6) Alt decreases, speed increases until overspeed.
7) At overspeed warning PF pulls nose up (realizes instrument error?) but does not recover (aeroelasticity?).
8) RIP.