Might be a dead display or a motherboard failure. (Friend of mine had that happen.) You could connect an external display to see whether the iBook fully boots... Then I'd back up the important files and have the iBook repaired. But since it's kinda old, the price for either a new display or a new motherboard will probably seem exorbitantly high.
Mac user since 1987. Running Mac OS X 10.8 Mountain Lion on a MacBook Air 11" & an iMac 27" and whatever's newest for my iPhone 4s, iPad 3 and AppleTV 2.
Apple Certified System Administrator 10.6, Apple Sales Professional 2008-2011, Apple Certified Mac Technician.