Where do you see the white page, after you log in?
Is there some error if you open browser console and reload the page at this point?
I can see the login page for your CMS just fine, obviously I can’t see what happens after that though.
One note, you don’t have Source and About links there, I’m sure those information are distributed to your customers in some other way, could you let me know how?
They need to be to comply with AGPLv3 open source licence terms.