My Apple TV (gen 2) shows a blank screen on start up. How do I fix? Not sure I have latest update loaded.

Hi, I have opened my Apple TV and it has a blank (black) screen. When I press Menu, I get the blip sound but can't get a picture. I have wiggled the HDMI cable. Not sure that I have latest update, and not sure how to find what version I have without a screen. Can I find this on my Mac. Help!