I was experimenting with alternative firmwares on my WD Cloud Gen2 and discovered this method downgrading to OS3 from OS5.
- upgrage to DSM ( https://fox-exe.ru/WDMyCloud/WDMyCloud-Mirror-Gen2/ )
- move on with the installation of DSM
- Enable “SSH Access” in web interface
Login via SSH from your first login (Or any of ligin with Admin privileges)
Type “sudo su” and enter your password again. You are “root” now. Type:
dd if=/dev/zero of=/dev/mtdblock1
- After reboot you can access to “WD Recovery” web. Install original WD firmware OS3