alessandro were you able to recover your nvr? I too am in the same situation. I was able to get it back in Chinese menus but I would prefer to put it back in English due to the language mismatch.
I have always exprienced issues with my nvr since i purchased it on ebay two years ago. To fix my issues i thought it would be a good idea to upgrade the firmware so i loaded firmwarw from an (ni) model nvr from the browser. All seemed to go well until it rebooted and i got the illegal cn beeps...