First of all, you must dissasemble the pda if you have some experience with that. There are some possible problems, one regarding the display connector to the motherboard and the other to the motherboard itself.Probably the display connector isn't atached firmly to the motherboard. There is a worse scenario where you may accidentaly burned some dc convertors on the mainboard when attemting to power on after the pda was dropped. If you can, dissasemble the pda, check the connectors, remove and reconect the back-up battery, and then, just to be shure, perform a hard reset.
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