iBook G4 sleeps but display does not turn on

Thanks. I tried that and got a little joy. I did get an angry BEEP and a little while later a startup sound and then some internal noises after trying the Power Manager trick. But then nothing for a long time. When I went back after a while I saw a slowly flickering light that I interpret as a sign the iBook is sleeping, and it starts to wake up after I press another key. But nothing after that. I do get a sign of light from the light on my optical mouth going on, and it's still on now. But there's not a sign of life from the screen, as if it's dead or not getting any power. I don't know what that might be.

Thanks for the suggestion. I tried a flashlight up close when the optical mouse was showing light (indicating power was on) and could not see any sign of a faint desktop. I did that after turning it on, when the Sleep light was on, and after I pressed a key to wake up the iBook, and the story was the same, the only ghost patterns were left from wiping the dust off the screen. It looks to me like there's no power going through the display, but I can't be sure.

That's a good idea. I have an Apple mini-VGA to VGA adapter and a monitor with both VGA and DVI ports, but can't find the crucial intermediate VGA cable, so I ordered one for $6 from Ebay to try. Thanks

Got the intermediate cable, hooked everything up, turned on the iBook and ... the display couldn't detect any signal from the iBook. It was a good idea, and well worth trying, but I wasn't surprised. The iBook is over 20 years old and it served me well for 6 of 7 years in the 2000s. I revived it several years ago by using a hot air gun to warm the solder enough to get current flowing, but I haven't been able to find the instructions needed to get the case open and back together afterwards. Fortunately, there's nothing essential on it.