Thanks, a hard reset was a little bit different on the Libra H20 - I had to use the page turning button together with the power button
After a hard reset the firmware was "downgraded" to my original version (i guess) and I logged in to my overdrive library - I was not able to browse any books.
After that I got a message to update and I got the latest version again - but it still says "Oops! Something went wrong" when I connect to Overdrive
(everything else is working just fine)