Zune does nothing! Screen says Zune with loading logo but...

Listen to the Zune as it is starting up, if you don't hear the hard drive spin it's a broken logic board. If you hear it spin, but it makes a repetitive noise, you have a hard drive issue. The Zune logic board isnot too hard to replace. A good source for the part would be ebay. ButThere is a stepby step guide too that explainshow to replace the board : Zune repair. There are also third party Zune repair companies that do it for you.

Let it on and completely drain the power, then try it. Make sure your lock key is not locked either. (at the top of Zune Device)