If I read correctly the wing went 1st, probably from impact on a tree and sparks or engine heat ignited the fuel. The rest was chain of events.
I still think the ruskis induced the situation, like altering the Glide Slope, etc.
From the report:
The wing tip shows a number of curls up to 450° seen as significant signs of explosion. In addition a long number of characteristic signs of explosion can be seen (Fig.2)[...]
Many pieces of the left wing, in the vicinity of the Bodin birch (bb), were found before the tree in an area of 41 meters north and 17 meters south in the direction perpendicular do the flight direction, and 43 meters to the east of the tree (Fig. nr.3)
Three pieces of the detachable part of the left wing were hanging on the branches of the so called Bodin birch (Fig.4)
Experiments conducted by the Committee in 2016 on an element in 1:1 scale with a similar shape and weight to one of the hanging elements showed that the distance needed to lose velocity, and to land on the branch is at least 100m and a height not less than 26m. One of the elements rammed into the trunk of the so called Bodin birch does not come from the hypothetical place of contact between the wing and the birch, and was identified as an element in the construction of the plane being 70cm closer to the fuselage, than then place of contact described by the MAK and Miller reports. (Fig. 5). A piece of the skin of the nose, to which the piece rammed into the birch tree trunk was attached, was identified over 200m further in the direction of flight-next to the Kutuzov street. A fragment of the spar, to which this piece was attached, was identified 400m further in the direction of flight in sector 10. (Fig. 6).
The plane exploded, and then fragments of the plane hit the tree.
In the report it said a door was blown off and impacted the ground at a much higher rate of speed than the plane itself, implying another explosive force blew it off.