goto edit the app:
https://mysite.com/admin/config/fb/application/app-id/edit

I get a white screen

this is in the logs

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'fb_admin_app_page' not found or invalid function name in menu_execute_active_handler() (line 517 of /includes/menu.inc).

is fb_admin_app_page defined anywhere?
fb.module:250: 'page callback' => 'fb_admin_app_page',

it might have changed to fb_admin_app_info but I'm not sure.