Powerbook G4 issues.

I have a 15 inch powerbook g4 I got a number of years ago, I am going through the process of getting it ready to be sold. I am running into a number of issues with it now. I have tried following instructions for how to erase all data but for some reason that won't happen. There are also a couple of other things that need to be fixed as well, spacebar, delete, and arrow keys do not work all the time, same with the keyboard dim. I had to reinstall OSX 10.3.7 as Tiger was not being recognized as installed when I tried to erase the data using disk utility. I will try everything possible to fix this so please give all the help you can.