Hi,
I have the same problem. I tried to change the WEBGUI PW over omv-firstaid, but the new Password doesn't work. This happened to me several times. I managed to change the admin PW for the Webgui over ssh and it worked but as soon as I tried to login next time, it didn't work again. Now nothing seems to work. My system disc isn't full and I haven't changed my Keyboard layout. I get the following message: "Software failure. Press left mouse button to continue. Falscher Benutzername oder Passwort (Wrong username or Password)".