Persian-language PDF whose title translates as hidden Android codes, 651 KB in size. Despite being filed as a schematic, the name suggests a list of secret dialer codes for Android phones rather than a circuit diagram. Such codes open service and test menus for checking the display, sensors, battery, radio and other hardware, and some trigger resets. Any PDF reader opens it. Codes vary by manufacturer and firmware, and certain ones can wipe user data, so confirm what a code does before entering it on a customer device.
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_mobile5. 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.