An M4 Pro display fault - diagnosed carefully first, because the tandem OLED panel is the costliest part in the device.
Service Details
The M4 Pro display is not an LCD. It is Ultra Retina XDR - two OLED panels stacked and driven together - and it is the single most expensive component in the iPad, which is worth saying out loud before anyone opens one.
So we diagnose properly first: lines, dead touch zones and black screens are not always the panel. Where it is, the assembly is lifted and replaced, the device resealed, and Face ID, touch across the whole surface, the 120Hz refresh and Apple Pencil Pro input all checked before handover.