(No WiFI and The digitizer screen not responding)

Thanks for the Help. I fool around with iPod as a hobby. I think they are petty neat the way they work, so I'm trying to learn all I can about troubleshooting. Right now I'm concentrating on two common problems I hear about a lot. (No WiFI and The digitizer screen not responding to the touch) Example: "Slide to Unlock" Digitizer will not sense your finger swipe. For both of these problems can it just be a fried motherboard causing the problem or could it be a broken or shorted wifi flex ribbon cable. Would you have any successions about this or would you know where I might be able to find more detailed information discussing these circuits or problem? And some homemade Diagram would Help? All Inputs will be Welcome..Thanks Again...