Full schematic PDF for the ASUS TUF B450M-PLUS GAMING motherboard, revision 1.0, 7.59 MB. Technicians rely on it to map the AM4 socket power stages, chipset rails, the BIOS flash circuit and the front panel and USB connections. It also shows the power-on sequence with enable and power-good signals, which helps pin down why a board powers on with no POST. Make sure the PCB revision matches 1.0 before trusting part values or net names, since later releases may differ.
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 @vinafix_bios. 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.