Bad controller or HD (3.0TB SATA WD30EFRX)

See the previous link posted if you haven’t already…

One suggestion. Disconnect any other drives if possible. One further suggestion is to not bother with Windows 10 and disconnect all drives but the My Cloud drive and run a Linux boot disk/live cd disk. That way one doesn’t take the risk of inadvertently accessing the Windows drive(s).

https://tutorials.ubuntu.com/tutorial/tutorial-burn-a-dvd-on-windows

https://tutorials.ubuntu.com/tutorial/tutorial-create-a-usb-stick-on-windows