Checkout Button No Longer Works


I recently upgraded from MarketPress Lite and installed MarketPress e-commerce. I had a quite a few migration tasks that I have figured out, but I'm unable to get the checkout button to function at all. It does not appear to do anything. My best guess is that there is something weird within the theme that I'm using.

I have tried a number of ideas, but cannot seem to get the checkout button within the mini cart or widget to start the checkout process. Please advise. Thanks!