PDF schematic whose name reads only i pad S9, roughly 1 MB in size, with no brand, board number or revision given. Because the name is that vague, open the document and read the title block to find out which device and mainboard it really covers before using it. When it matches your board, a schematic like this helps trace power rails, check charging and backlight circuits and locate the components behind a fault. Compare the PCB markings carefully, since tablet boards often come in several variants.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @smschematics. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.