Dead Pixel Test

In short A dead pixel gets no power and stays black on every colour. A stuck pixel is latched on and shows the same bright red, green or blue dot against every background. That distinction decides what you can do about it: a stuck pixel can sometimes be recovered by flashing colours at it, and a dead one never can. Before concluding either, wipe the screen — dust sits on the outside of the glass and moves or disappears with a dry microfibre cloth, while a pixel fault does not move. That single check accounts for most reported faults. Cycling through white, black, red, green and blue is what makes a fault impossible to hide, because each colour catches what the others mask: a dead pixel is obvious on white and invisible on black, and a stuck one is the reverse. On whether you can return it, most manufacturers write their policy against the ISO 9241-307 pixel fault classes, and most consumer panels are sold to a standard that permits several faulty sub-pixels before a return is accepted. Check the specific policy before assuming — the thresholds differ widely between brands and between monitor and phone.