FTP back to the folder that has the child theme (child-menu.php)
I’m not sure what that means. What is child-menu.php? Your child theme should be in a folder at the same level as your main theme; something like this:
/wp-content/themes/hueman
/wp-content/themes/hueman-child-master
Your child theme must have at least one file; style.css. It may contain other files like functions.php and other theme files that you’ve modified. If you want to start over with a clean child theme you can download one from within the Theme Options by clicking the Help tab in the upper right corner.
If you have your child theme set up correctly, the first thing I would recommend is using Notepad++ or Editpad to change the footer.php file. Using Wordpad may add extra formatting characters that cause problems with the php.