Schematic in PDF, 1.96 MB, centred on the SM7150 processor according to its name; the phone model and board revision are not stated. Opening it in any PDF viewer lets you search signal names and pinouts. Such SoC pages help trace core and peripheral power rails, check clock and reset lines, and narrow down shorts on the supply network near the CPU. Match the drawing to your specific handset before measuring, since implementations of the same chip differ between manufacturers.
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 .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.