How to open a WD My Cloud case & extract the HD
The video linked below worked like a charm for me to open the case on a Western Digital My Cloud drive:
Read more: Link - How to open a WD My Cloud Case - YouTube
(Disclaimer: I take no responsibility for any damages by following these instructions)
I used more than one credit card so that there was always a card still inserted on the other side.
In order to extract the hard drive, you can tilt it carefully so that you can access the screws that go through two of the rubber bushings that suspends the hard drive in the case. On my drive the screw heads were of an unusual standard, I think it is called "Torx" and luckily I had torx bits fitting.
Then remove the screws that mount the circuit board to the hard drive, and now you should be able to turn out the hard drive in the opposite direction of the circuit board. Use the torx screwdriver to remove the bushings on the other side of the drive, and then you need a hex screwdriver to remove the metal thingamajig that is on that side and now you should be left with a hard drive e.g. suitable for mounting in another case, or to be replaced with another drive.
Mine is now humming along in a USB 3.0 case, where the USB port is in slave mode opposed to the not-so-useful master mode on the WD My Cloud.