iBook G4 boots but no image on screen but able to access to open firmware

Hello everyone. I have a question and hope someone is able to help me.
I have an iBook G4 which was working fine. A week ago my little sister used the laptop and now I have the following problem:

a) The laptop boots because I get the boot chime, but the screen keeps black.
b) I connected an external monitor to check if the problem was the laptop monitor. When I start the computer, I get a gray screen (in the external monitor), but no apple icon apple and cannot pass from this gray screen.
c) I noticed that the caps lock light was not turning on, so I accessed the open firmware (keeping hold the power button - getting a weird chime and a light flashing near the case button - power chime ) and I got the open firmware screen (still in the external monitor) and I noticed that the keyboard was not working also! I connected an external keyboard (usb) and I am able to type.

I know I won't be able to use it as a normal computer because of this weird problem. I was thinking to keep it as a "desktop" with the external monitor and the external keyboard. My questions in this case are:

a) Is it there any way I can boot from cd from open firmware? (I cannot do the "keep the 'C' key hold during start up" because my laptop keyboard does not work.
b) Because I get the open firmware console, could this be a OS problem? What I mean is that if I reinstall the OS, could I at least keep using this computer as a desktop?

Hope someone can help me. Thank you!

Li wuen