My error started with "failed to mount"...so i removed the case and now just want to fix the partitions

Bennor: I did some more searching around the site and found a post/procedure you provided, with brilliant detail on copying img files to partitions on the drive. Based on the details I have provided, is this the best avenue for me to attempt?

You recommend starting with Step 13

From “MyCloud HD replacement again

You really seem to know your stuff here, so thank you very much for your guidance.
-W