Hello,
Just wanted to communicate this issue to anyone else who may experience it. I started to feel slight electric shocks through my guitar strings and on the metal stomp buttons on my Pod HD500X. After doing some troubleshooting, I found that it was the USB port on my computer that somehow got bent and was causing the electric shock. When I switched the USB cable to another port on my computer, the shock went away completely. Before you take it in to get repaired, give this a shot and see if it works.
EDIT: I have also been told by a guitar tech that incorrect grounding in your guitar can cause this problem. Try using another guitar with your pod to see if you experience the shock. If you do not, it is probably the guitar