Unable to edit Header in Mantra theme

I am an Administrator and trying to change the logo image in the Header. When I go into the admin section and go to Appearance > Header I get a blank page with a button saying “Edit Widget: Google Analytics Stats”, nothing happens when I click it. I can’t get to my Header section at all. Has anyone else seen this or know how to fix it?

The page I need help with: [log in to see the link]