It's better if you revert all your changes and let us see the first problem, now that you've already done something that I have no idea I cannot help and I cannot guess any reason.

I've changed out FA icons, and it has since broken the icons on the homepage of the forum. However, the icons show on other pages like recent posts. It seems like it would be a caching issue, but I do not have any caching plugins setup on the site. I wanted to use the FA car and bolt icons, but no matter what I try they do not show up. See screenshot. Any ideas what may be causing these issues?