I think discounting the unusual baro altitude data is a mistake.
Either it is telling the truth or there is a problem with the data recording (only Adrian can judge).
IF the baro sensor is telling the truth it is indicating a constant pressure in the av-bay for most of the flight and then a gradual increase in pressure up to the point of distruction. If everything was normal then the pressure should be on a generally decreasing trend.
This indicates to me that there was compression of volume of the av-bay right from the get-go. Indicating some structural failure or defect in the airframe right from the beginning.
Just a thought.....