A Spray Display is a quick, very cheap way to turn any flat surface into computer and video display. Installation requires placing a set of electrical control rods on the surface, then spraying several layers of conductive materials, a layer of fluorescing pixel elements and finally a transparent protective layer. The process generally takes a few hours to allow the layers to be applied, align themselves and dry properly. Display resolution is poor (600 µm pixel pitch is standard), and if not applied with care, there will be noticeable display artifacts.
The display is temporary, lasting a year or so before degrading, longer if in a protected environment, shorter if exposed to the elements like sunlight and harsh atmospheric conditions. There isn't any way to fix the display, it has to be removed and replaced.