*** THIS ISSUE HAS BEEN RESOLVED JUMP TO FIX ***
I upgraded my store from 5.1.1 to 5.1.2 by hand because the automatic upgrade still did not work.
I uploaded all files and ran the setup (upgrade).
EEVerything seems to work, but I had switched my store to offline before upgrade and now I can't put it online again.
When trying to change setting I get a blank page .....
What is going on?