Hi!
I’ve logged in and activated the plugin, but it’s not a javascript issue, since all the back-end fails.
Unfortunately the error reporting must be disabled, as there is no error message there. I’m suspecting either something very simple, or maybe a memory limit issue. It looks very strange, never seen this problem before.
However when I connected with FTP, I can only see an empty folder, I’m not able to see the site directory. Can you please check that?