SpaceX have been totally transparent with their launcher failures and are far and above any other organisation in this respect.
The previous helium tank failure was traced down to a 3 D 4" square area by interrogating strain gauge outputs and applying different filtration to the raw data to produce the result.
This showed that the support struts could have suffered oxygen intergranular corrosion.
This was proven when lab tests showed a number of the struts had a chemical imbalance that could lead to this type of weakening.
The support struts were then manufactured in house.