I upgraded my 2nd gen WD My Cloud OS5 from 4TB to 12TB (WD Red Plus 12TB). Had a lot of problems, because I always got red light after cloning 4TB to 12TB when I put it in the NAS. Since my 4TB WD My Cloud was already upgraded from OS3 to OS5, maybe there where the reason of my problems.
I tried Clonezilla, AOMEI and DiskGenius for cloning in various modes, but always same red light result. I have an old AM3 motherboard so I tried it on new AM4 B550 motherboard, but got same red light result. I tried to resize the data partition to 12TB, and not resize it to 12TB after cloning, but same red light result.
I almost gave up, but then a friend of mine said he has a HDD cloning device. You put first HDD in first slot and 2nd HDD in 2nd slot and press start, and it worked. I got finally stable blue light and could login to WD My Cloud with browser, but I could not read any data from it. I did a SYSTEM ONLY RESTORE in SETINGS/UTILITY that should preserve the cloned data, but I got an empty 4TB HDD on my 12TB drive.
So I cloned the drives again with HDD cloning device, but this time I resize the data partition on the new 12TB HDD. Data was also not readable when I put it in the NAS. I did SYSTEM ONLY RESTORE and got an empty 12TB NAS.
Then I connected my old 4TB to PC with serial ATA, and the WD MY Cloud NAS with 12TB on the network. Then boot in windows. Install Ext2 File System Driver from sourceforge.net and mount old 4TB drive in Windows. Then you can access your files and copy it to new HDD in NAS. After that I got finally my data in new 12TB NAS working.
I hope it helps someone to spare a lot of time I lost in trying to get it finally working.
