- My iBook G4's display shows nothing, but external monitoring works fine. I connected the computer to an external monitor and I can work the computer. I didn't crack the G4's display or anything like that - it just quit. When I use the external monitor and adjust the brightness and contrast from the G4's control panels, the *laptop's* blank display also brightens and darkens (though absolutely nothing is being displayed). Can you diagnose the problem with that information? Thank you.