I hope you guys’ iPhone are still working well. But if you are so unlucky that have dead pixel in your screen, you may try the new software PixelChecker available from the Cydia. It’s from the iSpaizo.net source, if you don’t have it, just install it from the list.

PixelChecker will help to check whether your screen have dead pixel by displaying different colours. Just tap the screen and the colours will be changed. After you tap it several times, it will flash the colours. Flashing colours can help to fix the dead pixel. No matter the iPhone have the dead pixel or not, it’s good to have a check.