Resetting Your Zune 80GB Device
If you can’t get the unlock button or the recharge function to bring your display back to life, try resetting the device.
Slide the “hold" button into the unlocked position. Next, press the back button, located on the top left side of the device. Hold it while pressing the top center of the Zune pad. Hold these two buttons together until the display lights up.
In most cases, one of these solutions should work to help you determine how to turn on the Zune 80GB display. Unless the whole device is malfunctioning, you shouldn’t actually have to wipe the Zune clean, firmware and all, and start off with a fresh slate.
Avoid resetting the device unless you really need to. You might also try sliding the “Hold" locking switch back and forth to kind of “wake up" the lock mechanism, which really only keeps you from inadvertently skipping songs and turning the volume up high.
To keep the battery charged and prevent the need to restart your device, turn your Zune off when finished using it; don’t just put it to sleep. To turn the device off, press the “Back" button at the top left of the device and the “Down" button on the bottom of the Zune pad.