Does the computer go past the Post screen you know memory check etc
or has he completely wiped the BIOS e.g. flashed it clean and it just turns on with just the power light
If the Computer doesnt POST then you either have to replace the BIOS chip physically or see if the system has a bios recovery option
As for formmatting the drive you can download a boot disk e.g. Win98 boot disck it has the formatting tools on it already and you wont have to take the Hard Drive out, it will just boot off floppy and all you will need to do is type
If the hard drive isnt showing check the Bios property’s make sure IDE identification set to auto detect or Auto. As for OS you can use whatever just set in the bios to boot off the CD drive.