What To Do... G4 won't boot up past grey/blue screen?

Don't think there is a hard drive problem. The computer has been sitting for quite some time (it's a backup). The battery is fine.... green light and all. I have also tried the various startup key codes (cm+opt+r+p, etc) but to no avail. I even put in the startup disc but no results.

Anyone have any suggestions? I like looking at the Apple Logo but I would like to get past it. I have never had any hard drive, etc. problems to date.... it's just been sitting for quite some time as I have a MacBook Pro now.

Thanks in advance for any assistance.