Chosen Solution
Since changing the battery in my 80gb classic, I’m only seeing the black and white ‘do not disconnect’ screen. I can see the ipod is connected to my mac by usb using the command: ioreg -p IOUSB -w0 | sed ’s/[^o]o //; s/@.$//’ | grep -v ‘^Root.*’ but I can’t see the disk in diskutil. Also, I can access neither diagnostic mode nor disk mode on the ipod. Any direction would be appreciated here, especially as to whether the HD or logic board might have died. Thanks!!
Disconnect the iPod from anything (computer, charger, etc). Press and hold the MENU and SELECT buttons at the same time for several seconds; the iPod will (or should) reboot. If that doesn’t work, connect the iPod to your computer and then, with the iPod still connected, restart the computer. When the computer restarts the iPod should show the “OK to Disconnect” message. Do so, and the iPod should be back to normal.