usually a white screen is your ribbon that connects two halves of phone, you can get them for about £3-4 off ebay, they are fiddley to fit but with a bit of patience its not to bad, theres a video on the net type in "d500 disassemble reassemble" on google you should find it. its free but if you want ebay does it with written instuctions for a quid or so. if you do try yourself to change ribbon be careful not to break the ribbon connector clip, not only are they hard to buy and dear fo what they are, ther a bugger to fit.
if its not ribbon it might need flashing and you need more gear for that.
hope this helps.
lockpicker
March 2007