Schematic diagram for a device coded G520-0000, provided as a 598 KB PDF; the Chinese text in the name translates to schematic. No brand is given, though the code resembles Huawei G-series numbering, which is not confirmed here. A compact circuit file like this is used to follow power rails, check charging and USB lines and locate components around a fault. View it in any PDF reader and compare the board marking and variant on the actual PCB before relying on part designators or measured 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 @Schematic_mobile_iran. 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.