have you tried what Bennor suggested Unbricking without opening ?
Is the MyBook just enclosure with SATA connector or is there chip on the SATA like in MyCloud? it might be that the chip is not recognising the OS on the MyCloud HDD… I wonder when you connect it via the MyBook enclosure to the ubuntu virtual machine do you check just the gparted if its connected or did you try to run terminal and run something like /proc/partitions or fdisk -l to see if the system can see the device but maybe it just didnt mount it properly
