Re: Thumb down?
as the feedback on the stick did not clearly show the nose up was from the other co-pilot
That is about it. One pilot realised what was happening but could not feel that the other pilot was holding the stick fully back - made worse by the way Airbus have put the sticks (basically a gaming joystick) in the cockpit sidewalls so one pilot would have to look across past the other to see what they are doing.
In a traditional "mechanical" system, the two sticks would be mechanically linked - so one plot would be able to feel what the other was doing. It was eventually realised what was happening, but not before they ran out of altitude in which to recover the situation.