After updating the X theme, things like tabs and icons stopped working so I tried to re-download the theme and manually re-install it by moving the original x folder and dragging the newly downloaded one into my themes folder. I then got the message: “Cornerstone is not validated. Place your Envato purchase code or Themeco license for instant access to automatic updates, support, and custom templates. Learn more about product validation or manage licenses directly in your Themeco account.”
I used the license key that is on my account page and where I was able to download the theme again. It tells me that the purchase code is invalid and to try again. Not sure what to try next.