Consider this in assessing the evidence. Unlike most fires in structural buildings, where fire loadings are somewhat static, the original ignition source in aircraft in-flight fires is not necessarily the area where most severe burning is experienced. Lab test may confirm this. Reconstruction may be necessary. Parts subjected to ground fire may have twigs, leaves, etc. outlined in soot pattern.
Explosions can occur with little to no thermal or soot evidence.
Structure damage may be best evidence of an explosion. Molten metal may be deposited by gravity, air flow, blast wave, or relative motion or a combination of the foregoing. Gas released from pressurized containers may given strange burn patterns. Nitrogen will tend to suppress the fire and high pressure air may give evidence similar to oxygen. Oxygen release may result in severe burning often resulting in a white ash deposit.