I have sound but no picture just thin white

its the hanna chip, this chip controles the grahpics side of the xbox and is held on the board by a method called bga (ball grid array) small balls of solder connecting it to the motherboard. when the xbox heats up and cools down every time you play it very slowly unseats from the motherboard there are fixes for it but require a somewhat risky fix or it can be sent off to a specialist repair shop to be reflowed (chip resoldered), i personally would look on ebay for a second hand console can be cheaper than a repair.hope this helps.