Very interesting !
That would be 15s from 190 kph to 230 kph.
That's an eternity.
and that with TOGA thrust.
Definitely something wrong here.
Are you sure they had TOGO power? The FE didn't respond after the first command by the captain, though it might have been missed on the recorder. My interpretation is that the FE didn't apply TOGO power until after the second command, which was 21 sec later.
Stuck brakes would indeed create a strong Nose Down moment as long as they were on concrete. Only after getting on the grass and 'jumping' a bit downhill, the Nose of the Aircraft starts to rotate. Given the fact that the factor of adhesion would be very much reduced at that moment and considering the bounce after the bump when leaving the runway a subsequent rotation seems plausible.
If the retarding force is so high, then how did the aircraft get to V1 in only 20 seconds at nominal power? (assuming 190 is V1) Any extra drag would have significantly slowed the aircraft down and extended the time to V1.
Further, some earlier quotes from the investigators say there were no visible skid marks found on the runway. If the parking brake was applied, as the aircraft gained speed, and the wing gained lift, things would reach a point where the wheels would lock and there would be obvious skid marks on the runway.
The story with the breaks seems to match most of the known.
I disagree. Speed brakes, maybe, but unlikely. Wrong CG, also unlikely, but perhaps a greater possibility than brakes.