This thread reminds a little of the story where after paint, a pilot took off and the controls were rigged wrong...turning the yoke left, meant a right turn, and visa versa...he couldn't figure it out, and crashed.
It wouldn't surprise that a pilot trying to get the speed up, pushes on the yoke, but the fly by wire, now with reverse commands pitches up...the pilot keeps pushing forward...and at cruise speed and this condition...a 3k climb would be nothing, it would happen fast...
If the A/S tape was reading wrong as well...low speed meant high speed etc...it would all happen pretty quick..
Maybe lighting from a thunderstorm zapped the computer...
One more reason to use the radar, and have a plane that can actually get up to FL450.
Just a thought.