From what I remember, it is an XFS filesystem, when it supposedly failed I attempted to repair it with xfs.fsck which made things worse and I strongly suspect it was actually the cable at fault which I did confirm was bad. Hindsight is great like that.
I also would be interested in ways to confirm the drives health, confirm that it was the cable that caused the issue, the drive was just a backup drive and had very low read/writes and I would not be bothered by giving up on recovering it and just formatting and bringing it back into use for backup.
Also check what SMART attributes on the drive say - it will help confirm that the drive isn't broken in other ways.
I don't know of a good resource documenting what to follow from there, but make sure you don't touch the original in any way so you can always go back.
Otherwise, look at bits separately - those are documented in various blogs - how to analyse the partitions, how to recover the filesystem, how to find binary files without the filesystem structure. Projects for reverse engineering like binwalk may also be useful here.
And there are (CD or USB stick) bootable distros for recovering disks in bricked computers or just copying the data off the main HD to make a recovery disk. https://www.techradar.com/best/best-linux-repair-and-rescue-...
I recall using TestDisk above and SystemRescueCD.