Some issues found in the guide page should be fixed. 
 
If the guide page is enabled in "General MFA settings" and the user gets the message of "Unable to authenticate" a box is displayed below the log out button. The link of the "MFA user guide" takes the user to a new page <wwwroot>/admin/tool/mfa/guide.php where the user can see some information  from "Guidance page content"  (in the General MFA settings)
 
This page needs to be review. 
1- A warning is display (Note: The message is hidden behind the top navigation)

Warning: Undefined property: stdClass::$tool_mfa_authenticated in /var/www/html/moodles/mfa_dev/moodle/admin/tool/mfa/guide.php on line 40 

Skip to main content
2- If the user is not login, the top navigation and the secondary menu should not be display. 
Note: if the user clicks on any of the links from the menus it will redirect him to an error page or the previous page (Unable to authenticate)
 
I've created a video for this in case is not clear.