It seems that, in order to correct an indicated rudder problem, the captain pulled a breaker. That disconnected the autopilot, resulting in the controls becoming more sensitive. The captain did not verbally 'take control' of the aircraft, and because the Airbus uses sidesticks, he could not see what the first officer was doing. When he tried to correct the nose up attitude the system averaged out the control inputs and the aircraft stalled. Altogether a very sorry tale of poor crew training / cockpit management.