Schematic in PDF for the ASUS X555LI, 1.22 MB, with an RG suffix in the name that is not explained. Any PDF viewer opens it, and text search helps find net names, connectors and part designators. Technicians use the diagrams to trace power rails, check the power-on sequence, find where a short sits and identify signals on the graphics and charging circuits. Confirm that your board revision matches the one on the title block, because ASUS changes parts and nets between revisions.
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 @schematicslaptop. 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.