>>16751930
Flight 9 mishaps
>booster exploded 1km above water due to a rupture in the downcomer caused by an aggressive angle of attack during boostback (up to 17 degrees), which then caused propellant mixing and ignition
>three minutes into starships burn, sensors detected a methane leak from the main fuel tank into the nosecone (if I understood it right)
>after SECO at the correct velocity the nosecone was vented as planned, but the increased pressure in the nose cone caused an increasing attitude error
>the payload deploy was skipped due to the wrong attitude (ship was spinning), the high pressure also fucked the door mechanism somehow
>attitude error was corrected with RCTs, but there was still a leak into the nose cone so after nose cone venting started again
>due to the ongoing leak, the in-space burn test was skipped and subsequently all propellant was vented into space and the vehicle was passivated
>the root cause was "main fuel tank pressurization system diffuser"

so there was some kind of leak in a fuel diffuser that was located in the nose cone, which then leaked into the nose cone, which when vented overpowered the reaction control thrusters (and I guess if not vented would have caused an explosion or something perhaps?)