You need to state at least with which platform, which browser and which operating system. Otherwise we won't really be able to do anything to help.

My computer has Windows 7 32 bit, and Firefox 43.0.1.

Do you see any errors in the developer console while you load the page?
You are using an older version of Firefox. The latest version is 59.0.2. Perhaps doing an upgrade may resolve your problem.

Possibly related to : https://mecabricks.com/en/forum/topic/971/1

That may be the issue. I think that ECMAScript 6 support (JavaScript version required) has only been added in FF from version 52.

There are no errors, just a blank page...
I'll update firefox and let you know if it works,
thanks for the help!