Ok, instead of what hlekinfr suggested above I tried something else.
By searching the forum I found another post by hlekinfr uploading his
X9310BT user backup folder (http://avic411.com/index.php?/topic/80807-moderators-please-remove-condis-hackmode-v221/?hl=%2Bsuper+%2Btestmode&do=findComment&comment=331750).
By going to http://home.comcast.net/~cinful75/x9310bt/ I used the supertestmode to boot into maintenance.
I copied all the folders/datas from my avic-f930bt on the sd-card (I finally made a backup by this).
Then i compared prg0 und prg1 at the X9310BT user backup to point out what was different/missing
compared to my f930bt prg0 and prg1.
So prg0 and prg1 have to have basicly the same folders and datas so I coypied from prg0 to prg1 what was missing (if you have the same issues try to find out whats different with your avic, maybe you have to do it a little bit different) and deleted the old av.exe replacing it with the av.exe from X9310BT user backup.
After that I copied everything to my sd, booted into testmode, replaced the folders (don't forget to unmount the sd) and booted anew.
Finally I can use my avic before the trouble I had with gwenys hackremoval.
At this point I would like to recommend everyone who wants to delete/rewrite the password to use the supertesmode!!
It's all you need and it's less trouble!!