Fire Vs explosive failure
I agree that a fire alone would not create any loss of thrust and there would therefore be no immediate reason to abort take off. However, we do not yet know, if there was afire, what was the cause.
The report of wheel tracks off the runway add weight to my theory that the aircraft landed back on the tarmac and then suffered loss of control authority - for whatever reason. Did the stb clamshell activate alone with no thrust on the port side or did the port clamshell fail to operate as both engines were being used with reversers in an attempt to arrest the aircraft?
The topography at Madrid seems to have contributed to the break up of the aircraft in the 'ravine'. Had it skidded acorss flat fields and even wiped off the undercarriage I would be suprised if the force involved would have resulted in complete break up- there is plenty of evidence to suggest not.
So the crew perhaps took the correct action but then went off a cliff, whilst still within the airport perimeter - tragic!