Schematic PDF for the Lenovo NM-A221 board, an LCFC design, about 1.57 MB in size. Beyond the board number, the name lists no laptop model or revision, so identify the hardware from the PCB marking. Other copies of this number are titled ThinkPad Edge E550, but check your own board. The drawings let you trace power rails from the adapter input through the regulators, read how the circuits connect, and work out which components feed a faulty net. Compare the revision silkscreened on the board before trusting part values or pin assignments.
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 @pepeelectronica. 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.