After trying a firmware update for the LG GH22NP20 ...
The file executes in regular environment, and apparently didn't
screw anything up, and did make a few changes, but nothing like
gettring the drive back to normal. ... Guess there's not much point
in putting this in a different machine to see if it behaves differently,
I feel like the drive itself is what suffered any changes that occurred.

As the firmware update presumably completely overwrites the original
firmware, you have disproved my theory that the firmware coincidentally
failed.

Nevertheless... You should still test the drive in another machine. That's
the only way to know "fer shur" where the problem lies.