It could be either I’d imagine. Main issue with these is bad caps, but I‘m not sure what the LCD will display when they’re completely dead. Mine were failing, but it could still display an image. At a minimum the caps will need to be replaced, but it could also be a cable as I’ve had white screen issues on a later PowerBook be caused by one. The cap gunk can also destroy the internal screen ribbon, which can cause issues. You won’t be able to know until you’ve opened it up and recapped it.
Other than that, it’s just the usual brittle plastics, bad hard drives, and broken screen hinges.