The aircraft is alleged to have been over-fuelled and possibly over weight; full tanks transmitted the force and made damage worse.
The aircraft was below V1 when the fire started, and should have stopped. It is thought that the captain made the (probably sound) decision to get airborne even so due to the difficulty in directional control. From what I heard they would still have survived had the engineer not shut down the engines. You don't shut down engines in a fire until flight path is stable and the Captain deems the power is no longer needed.
oldchina
None of which caused a crash.