The Dashboard missing post firmware upgrade after using the unbricking procedure on a My Cloud, especially when replacing the drive, is a known issue that several of us have run into. I document my experience with this issue and my solution to this issue in the following thread.
https://community.wd.com/t/unbrick-then-firmware-upgrade-equals-no-dashboard/136666
The solution for me (and some others) is to fix the GPT table at the start of the unbrick procedure by running a sudo gdisk /dev/sdx command.
