As previously indicated you can try to reflash the My Cloud Firmware, either using the Dashboard (if one can reach the Dashboard) or via SSH (if one can reach SSH).
https://community.wd.com/t/how-to-firmware-update-via-ssh/95476/2
If that fails (which it appears it may have per your first post) then you may end up having to unbrick. There is some discussion on unbricking without opening the My Cloud in the following thread.
