You are almost certainly shorting something. Are you sure you are running the ribbon cable over the Pi and not the opposite way?
Please post a picture of your setup. Checking your soldering is also good advice, if you got any bridge you'll get into trouble.
Last, although probably not that relevant, I'm not 100% clear what Pi you are trying to connect. Please run:
curl -sS get.pimoroni.com/cpuinfo | bash(and post the result here)