What is this cable for and can I replace it separately?

Last week my trusted iBook G4 (12", 1.2GHz) suddenly stopped working. Mid-flight the screen went black. Since then I occasionally get it to boot up only to do the same thing over within a minute or two. Most of the time it does not boot, however. Sometimes with the boot sound sometimes it just stays dark but the fan and the HD are on. At first I though it was the motherboard, possibly the loose connection issue on the graphics chip, described elsewhere. Now that I took it apart to remove the hard drive to put into a new machine I bought I saw a broken cable near the left hinge of the screen. It is black and runs parallel to the video cable (shielded). I believe it is the microphone cable.

Is that correct?

Could this broken cable cause the symptoms?

Can I replace just this cable or will I need to do the entire video cable assembly?

Seems like a regular three strand cable and I think I should be able to patch it or replace it with another one.

Any thoughts/advice?