Glad to hear all is well. -ish.
Then I replaced the SATA data cable which I'm sure was new
FWIW, I have had at least one SATA data cable that was faulty from new.
This was some years ago, but I added a new HDD, and bought a new cable for it. It seemed to be working OK but when I looked at some of the system stats (don't remember what, exactly) it was recording countless read errors.
Reseating the cables made no difference, but just before sending back the disk as DOA I tried swapping cables with another disk, and proved it was cable not disk at fault. Ever since then I have been quite fussy about Sata cables, preferring branded cables from a trusted supplier like RS...