My basement flooded and My Cloud EX was submerged. Motherboard of the NAS was completely destroyed but another HD and its partitions are recognized with WIN11 as Disk 1. Are there any means to recover the files using WIN11 computer?
YEs.
You need a Linux file reader program.
WD OS5 disks are formatted as EXT4 (a linux protocol). Native windows will not read the disks. This presumes that your disk was a raid 1 (mirrored) and not stripped (default is mirrored).
(REMINDER: Flood is “common mode failure” for a dual disk NAS unit. So is “Fire”. Always have an offsite backup) (And maybe don’t put electronics in a basement. 
) (and yes, I had water in a basement as well - - -but the NAS units were in a house 120 miles away, about 600’ above sealevel)
