Before opening your iPod, ensure that the hold switch is in the locked position.
Opening the iPod can be challenging. Don't get discouraged if it takes you a few tries before the iPod is opened.
Insert a plastic iPod opening tool in the seam between the plastic front and metal back of the iPod. Once you've inserted the tool, run it along the seam to free the tabs holding the iPod together.
Continue to run the opening tool along the side of the case until all the tabs have been released.