How do they root cause something like this when so much of the evidence is blown to pieces?
Then there is all the video and film footage. I bet some of it was high speed (so the resulting film will be slow motion). Slo-mo film helps show the exact sequence of failures and was a big part of the Challenger investigation.
Finally, there will be a ton of data that was collected from the rocket in its brief flight.
Guess we've come a long way from a magnifying glass investigations :)
Each single professor explained us why their subject was the reason for Ariane V to explode. The physics one went about how the imperial/metric discrepancy was the cause, the mechanics one went about how error margin management wad the cause, the CS one about integer overflow... Each of them made it clear that their course was the center of the world, but altogether it didn't look smart.
I chose that the CS guy was right ;)