You have this solution:
http://anionix.ddns.net/WDMyCloud/WDMyCloud-Gen1/Recovery/Readme-en.txt
Or you open your MyCloud and you follow these tutorials:
http://anionix.ddns.net/WDMyCloud/WDMyCloud-Gen1/Replace%20HDD%20-%20English.txt
Another faster solution, but you still have to open it: [GUIDE] Debrick a completely dead MyCloud
To open it without damaging it: How to open a WD My Cloud Case - YouTube
