Source: https://drive.google.com/open?id=1h8OXgR8zlmMuYh0X7NsVrF2-Hn1rl5xj
Mirror: https://fox-exe.ru/WDMyCloud/

=======================================================================================

Howto replace or restore original firmware:

* You can use any of *nix system. I use Debian (Ubuntu similar).
* All command runing from root user. Or use Sudo.
* First thing after boot in liveCD - install software: apt-get update && apt-get install mdadm parted

!! For install new HDD - go from p.1. If you repare exist HDD - go to p.8-2

1. Use fdisk -l (or parted -l) for see what name have you WD's HDD.
* For me - its /dev/sdb. Replace it to your hdd name!
2. Run parted utility:
parted /dev/sdb

3. Type "print" for see what partitions exist on disk
4. Remove all: Type "remove 1" (where 1 - number of partition)
5. Crete new table:
mklabel gpt
mkpart primary 528M 2576M
mkpart primary 2576M 4624M
mkpart primary 16M 528M
mkpart primary 4828M 100%
mkpart primary 4624M 4724M
mkpart primary 4724M 4824M
mkpart primary 4824M 4826M
mkpart primary 4826M 4828M
set 1 raid on
set 2 raid on

6. Ok, type "quit"

7. Format data partition:
mkfs -t ext4 /dev/sdb4
mkswap /dev/sdb3

8. Stop automatically loaded md raid (If need) and create new, normal (You can get errors "Not found". Its normal):
mdadm --stop /dev/md*
mdadm -A /dev/md0 /dev/sdb1 /dev/sdb2
mdadm --create /dev/md0 --level=1 --metadata=0.9 --raid-devices=2 /dev/sdb1 /dev/sdb2
	# Type "watch cat /proc/mdstat" and wait 100%. Then - [ctrl] + [c] for close.

9. Use data partition as download folder:
mount -t ext4 /dev/sdb4 /mnt
cd /mnt

10. Download one of arhive's to /mnt folder:
v3.04.01-230: https://fox-exe.ru/WDMyCloud/WDMyCloud-Gen1/Backups/original_v03.04.01-230.tar.gz
v4.01.02-417: https://fox-exe.ru/WDMyCloud/WDMyCloud-Gen1/Backups/original_v04.01.02-417.tar.gz

11. Extract by console:
tar xvfz original_v3.04.01-230.tar.gz

12. Ok. Upload backup images to WD's hdd:
dd if=kernel.img of=/dev/sdb5
dd if=kernel.img of=/dev/sdb6
dd if=config.img of=/dev/sdb7
dd if=config.img of=/dev/sdb8
dd if=rootfs.img of=/dev/md0

13. Tell device to Fresh install (Fix for "0 MB usage" in webgui)
mkdir /mnt/hdd
mount /dev/md0 /mnt/hdd
touch /mnt/hdd/etc/.fresh_install
umount /mnt/hdd

14. Shutdown PC. (Or use "Logout" in menu)
shutdown -p -H 0

15. Connect HDD to WD's plate and turn on WDMyCloud. Wait ~5-10 min.