Full schematic in PDF for the MI2 mainboard at the P4 build, with 0917 most likely the drawing date. This circuit set is the companion to the separate MI2 P4 top and bottom placement files and covers the power management, charging, memory, display and radio blocks. A technician uses it to trace a missing voltage back to its regulator, check signal continuity, and match designators to parts on the PCB. Make sure the phone actually carries a P4 board, since component numbering can change between builds.
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 @mobileschematicshub. 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.