Xiaomi Redmi Note 9 schematic diagram, according to the name, though the file is catalogued under BIOS and firmware, packed in a 17.8 MB RAR archive. Expect circuit drawings for the phone mainboard showing PMIC, charging, display, camera and RF sections. Technicians use these to trace supply lines, find the right capacitors around a shorted rail and check connector pinouts. Several Redmi Note 9 variants exist on different platforms, so compare the board marking in your handset with the drawings after extracting the archive.
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 @mischematic. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →