Contribution d'origine par : Gabe ,
You can check the connectors between the display and the logic board and ensure it's connected by following [guide|1554|this] guide. If it still doesn't work then it could either be the logic board or the display. The best thing to do at this point is to find a friend with an old 3Gs and swap display! If it works, then the old display is broken. If it doesn't work, then it's the logic board. You can find the display [http://www.ifixit.com/iPhone-Parts/iPhone-3GS#0-Front+Panels|here] and the logic board [http://www.ebay.com/sch/?_from=R40&_trksid=m570&_nkw=3gs+logic+board&_sacat=See-All-Categories|here].