Password problems in Iview2 - how can it be reset?

I am running Iview 2-306 under Hyper-V.

I just updated the superadmin password to something like "11+ß()1f1,.-A1111ÖÄÜ".

Now I cannot login the the WebGui anymore. It says "Wrong username / password".

Is there a limitation on allowed password characters?

--> Do I have to reinstall the whole thing or is there a way to reset the password from the console or before starting up like it was on the 9.x?