Powerbook G4 white screen of death, tried everything with no luck?

A few days ago my powerbook g4 powerpc with mac os 10.5 froze. I held the power on down to shutdown and then pressed again to turn it back on. However, since then all I get is a blank white screen. I've tried many of the suggestions littered around message boards such as reset the pram with no luck. Holding the shift on to start in safe-mode has no effect. Holding down the option key brings up a screen with 3 icons: a reload symbol, a symbol for my Macintosh HD and a right arrow symbol. Clicking on the right arrow just takes me back to the white screen of death. Holding down apple-s to enter single-user mode has no effect. I can't find the install cd that came with my powerbook, can any 10.5 install cd I get my hands on work? Just out of desperation I tried a 10.5 upgrade cd with no effect. Also, I haven't tried command-option-o-f to reset nvram. If neither of these 2 remaining options work, is my laptop done for? Also, seeing that symbol for my HD, does that mean my HD is ok and it's something else? I was hoping worst case I could take my HD out and place inside an enclosure and connect to another machine. Any help is greatly appreciated.