Step 22
Turn the G4 over.
Remove the three T8 Torx screws from the logic board.
Be sure not to lose the rubber washers protecting the logic board from the lower two screws.
Step 23
Disconnect the indicated connectors from the logic board, removing tape as necessary.
Step 24
Carefully lift the logic board up and pull it away from you.
This step requires some force, but if the logic board will not come up, make sure you have removed all screws and connectors necessary.
Remove the logic board from the computer.