hard to say - can you see it in iTunes? can you do a restore?

Once the battery has run down it will switch itself off - give it a few days. Maybe after that connecting it to a charging source will sort all out

It's perhaps a software bug? So, I suggest you follow these instruction from Apple to reset your iPod.

Learn how to reset or restart iPod following a freeze. Tip: Check out this helpful movie too.

Important: If your iPod is frozen or won't turn on, it may be because iPod is paused or the Hold switch is in the locked position. If so, a lock symbol appears on the screen. Slide the Hold switch to the unlocked position and check the screen.

If the iPod is connected to a computer and displays any of the following messages you should eject the iPod from within iTunes instead of resetting it:

• Connected. Eject before disconnecting
• Sync in Progress. Please wait...
• Do not disconnect

If your iPod is frozen or won't turn on, the steps to reset it vary by model. You caneasily tell which iPod model you have if you're not sure.

screen is freeze, cant turn it off

screen is freeze, can`t turn it off

hold down the center button and the menu button at the same time and that will reset it.