Schematic in PDF format for Lenovo board NM-A281, revision 0.4 as given in the name, 1.58 MB. The NM-xxxx numbering is used by LCFC, Lenovo's in-house ODM. The sheets cover power rails, charger and system supplies, the embedded controller and connector pinouts, which helps when following a missing voltage or diagnosing a no-boot board. Check that the revision printed beside the board number on the PCB matches r04, since component values and placement can change 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 @cyberlanelectonik. 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.