update
From Aviation Law Service;
An unconfirmed account has it that a person in the cockpit fell onto the pedestal; in a 16 November press release, Etihad maintained that none of its staff were involved in the accident. The investigation is centered around the nose wheel steering, which was reportedly unlocked in order for the airplane to move out of the area after the tests had been conducted. It was apparently locked again for an unknown reason, putting the aircraft in front of the wall with engines running. The accident site makes sense if someone forgot to re-engage the nose wheel steering before heading to the exit taxiway. Then, the person lunging for the switch (to help the apparent lack of directional control) fell across the throttles – this at least is a reasonable scenario.
A few years ago there was a similar accident at Vancouver, Canada involving an engine test run on the ground of an Airbus A310. In that case, only line maintenance chocks were used during the engine run (as opposed to Airbus special ground run chocks that cannot be jumped). In the Vancouver case, avionics technicians pulled a circuit breaker that put the aircraft’s computers into flight mode. Presto! The engines went to flight idle, there was no reverse thrust, brakes or nose-wheel steering. The airplane jumped its chocks so fast the mechanics in the left and right cockpit seats did not know what happened (and they were not aware of avionics technicians fiddling with the circuit breakers). The airplane basically was on an uncontrolled taxi, right into a ground equipment building, and with enough force to shear off 6-inch steel I-beams.