Small 51.2 KB PDF named for the Redmi K30 Pro (spelled Remi in the name), with no board number or revision given. At this size it is likely only a few pages, such as a partial diagram, point map or component sheet, rather than a full schematic set, so open it first to see what it covers. Material like this helps locate components and measuring points around a fault area. Confirm the board version of the phone matches before trusting component locations or values.
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 @canalesquematicos. 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.