After several attempts I was able to close the update notification. But unfortunately this costs the access to the e-mail account of my university. I will try to reinstall it, but yesterday I could not gain access again and the google play service does not show the update hook anymore. Any idea what I can do?
Many thanks
Update: I just grabbed my phone after a quiet night and the update came back. :(
Update 2: Now I went back to factory settings. For now the upgrade process stopped and my cell says the update of January, 5th is installed.
Good luck for all of you