that replacement fail with the same issue

They said on the 4TB that singular files were being dropped/lost (likely hitting some magical number of files and oldest one falls out of controller memory or something stupid like that). This new one has the entire drive inaccessible completely. The 4TB makes sense as a firmware issue that was patched. The 3TB one sounds more like a controller failure IMO… I would call these different modes of failure. But there’s not a single shred of evidence that they’ve even looked at any of that. That’s my problem. There’s no journalistic work here except “see drive dead”. And if the 3TB failure is as I described… then it’s literally a “it happens”.