I took out the disk on bay 2 out of the IX2 and woops it booted again, so I recovered the data.
I inserted the cleaned HDD into the IX2 (Not a new one, it was the corrupted one), powered it up and magic did not happened! The red light turned on again and it never went off!
Now I am with an untouched HDD and a clean one (the one it was corrupted at first) but none of them boots the IX2.
So the disk which booted the IX2 after removing the other now doesn't work anymore? Did you do anything with that disk that you didn't tell here?
According to your tests both disks are fine, yet they don't work in your NAS anymore. I wonder if there is a power problem. The external power supply, or the internal DC/DC convertors might be broken, having not enough juice anymore to power both disks, and degrading further, not enough juice to power a single disk.
Do I have to format the flash drive in a special way?
Not that I'm aware of. As long as Linux can mount it using the vfat driver it should be fine. But some people reported some usb sticks to fail. So maybe there is a hardware constraint, maybe a timing issue
And sorry for my bad English… I’m from Argentina… I hope you can understand what I did.
Your English is fine. At least the written variant.