Cracked screen? Touch not working? Bad OLED display? Use this guide to restore your iPhone X to perfect working order with a new screen, a.k.a. display assembly.
The combined earpiece speaker + sensor assembly affixed to the back of the display is paired to your individual iPhone from the factory, so you must transfer it from your old display to your new one during any display replacement. It contains the flood illuminator, which is part of the biometric Face ID security feature. If it is damaged or replaced, Face ID will cease to function, so take extra care not to damage any of these components during this procedure. If damaged, only Apple can restore Face ID function.