OH. . . and pour out a big, big cup of patience. You may be in for some googling and learning a few things.
1st. . .I don’t have all the answers, but this does not sound hopeless. Sounds like you have a fried NAS unit (motherboard?). That does not translate necessarily into lost data. (maybe, but maybe not). I presume that Support took you through both 4 second and 40 second resets of the unit?
2nd . . .I took a glance at UFS. I am not sure this will work with a fried NAS box. BUT. . .with simple Raid1; where the data drives are MIRRORED; you may not need sophisticated software. The key is to get a hard drive attached to a working system. The drives should be identical. . .it doesn’t matter which one you hook up to a system. . . .
3rd. . . BUT. . .you probably need an external USB enclosure to make this happen. (or. . .install the drive into a PC as a secondary drive). The KEY here is that fact that the WD drives are formatted for Linux, not a PC or MAC format. Fundamentally, once you attached a drive to a working computer (say. . .through an external USB enclosure) you will need a piece of software to read the Linux file structure.
4th. . . and. . . I have already told you more than I know. I have not done this myself. If you do a search on “Data recovery” or “Bricked MyCloud”, I am sure you will find more detailed instructions (and exactly what software you should run to get the data). You can try looking in this sub-forum or the “MyCloud” subforum.
5th. … . You may be able to just get a fresh EX2ultra unit and install the drives. That just might work as well. The DEFAULT will be to wipe the drives after insertion. . .but there should be an option to simply use the drives. NOTE: for this to work, I believe you need another EX2 Ultra (i.e. something running the same firmware) This is NOT an upgrade opportunity to buy a Synology or Qnap. FWIW: If this happened to me, I would attempt data recovery using the steps above BEFORE trying a new NAS box.
6th. . . .there are plenty of people on this forum with experience with trashed systems. I am sure someone can provide more help than me.