This is good news. Hans Koenigsmann just did a press conference with Kathy Lueders in which they announced the root cause of the explosion. Apparently it was a failed check valve prior to the test as they were pressurizing, that resulted in some NTO setting fire to titanium piping, causing an overpressure which then cascaded to mixing of the hypergolics. At least that’s my preliminary understanding. They’re going to go from check valves to burst disks, and the fix doesn’t seem to be on the critical path to getting to a November flight.
[Update a couple minutes later]
[Update a few minutes later]
Here is the full SpaceX statement. And “hyperbolic” typo fixed in initial post.