A quick update on this
I'm having help form runandhide05 who is amazingly kind with me, answering all my questions in PM.
I have a Wi-Fi only 8.2 Xoom 2 bought in France so I have flashed this ROM : 0.268.4.MZ607.Retail.en.FR.
I could boot but when I tried to update OTA it failed. It downloads, start updating and fails so I am stuck in 3.2.2.
Also whenever I reach the page of an application in the Android Market, the Android Market quits.
Finally adb doesn't see my device.
I've tried flashing another ROM with the same result : 0.281.8.MZ607.NonEFIGSRetail.en.EU
All this is very new to me, I feel like I have learned a lot in 24 ours but I really have no idea were to go to solve this and feel like I am asking a lot to runandhide05 at the moment so if anyone as "qualified" as him had any idea to help it would be amazing.
… again runandhide05, thank you so much for all your help so far.