cracked iPod touch 4th generartion badly damaged screen
Watch out for the tiny ribbon cable that controls the external volume and power off switch. It can rip very easily. It is located under the metal shield above the three tiny screws that hold the shield in place. When removing the shield, you do not need to pry all the way under the shield, just under the thin shield itself in the corner. You will see that there is another part under this shield which does not need to be pried up, or else you'll rip the cable. If you do, the iPod wont turn off by the switch and you will not be able to control the volume by the buttons, but it still works with the internal volume slider on the screen.