Data corrupted: where to start?

After few days of exchange with the support and sending system report: data corrupted and I can’t even reapply a firmware update.
I can access my MBL, old shares are there but empty but I see that 1.2 To out of 2 To are here. I can also create new shares upload/download to the shared folder but not the old ones. I can access the dashboard, ssh and new shares only.

Any recommandations to try to recover a corrupted system or files?

Any suggestions much appreciated!

see my response on your other post.

Pull the disk out the enclosure. Attach to a computer running linux or at least some software that allows it to read linux formated disks. Then look around in the disk to see if you can find the data. If you can, then copy to the computer.