Hi xcobar,
Since you were able to get your data form your My Cloud by mounting the partion that some what rules out data corruption. There are methods to restore the factory image but, it will void your My Cloud warranty because the internal drive must be removed and connected to a computer to image the drive.
Other option if your warranty is still valid you can contact WDC for an RMA to unbrick your drive (or replace it per WDC).
I personally perform a reimage on my drive should I brick it just for the experience as others have done it too. I would only recommend this approach if you fully understand the linux re-imaging process.
Again, drive removal & re-imaging your My CLoud will void its WDC Warrant.
Here is the thread to re-image your drive:
Here is the image for a 2TB system: (Note to Modierator - feel free to strip this link if not in line with WDC TOS)
https://mega.co.nz/#!PElwgSyJ!Aicrq1FKKojLVjJgBAz37Sa-9F1KaPeeyMhZ3lN2vpg
I personally have not done a Drive Image Restore as of yet but, I will do one for anyone I meet locally in So. Calif that desires one.
