PowerBook - Pismo keyboard and trackpad woes

I know this is ancient technology but someone may remember a solution... My keyboard and trackpad have ceased to function. The caps light and another one to the left of the F5 button have come on. Luckily I have a Logitech wireless keyboard and mouse so I can use the machine. I've tried undoing and re-plugging the keyboard assembly. I'm trying to work out if this is a software or hardware problem. If the former, would a system re-install help? If the latter would a replacement keyboard make the trackpad come to life again? Any ideas gratefully received... Tony
Mac OS x Tiger Igig memory