Spanish-language guide titled Principales fallas en celulares, the main faults in mobile phones, a 1.34 MB PDF not tied to a specific model or brand. Such material typically covers common failures such as no power, no charging, no display, no signal and audio faults, with the usual suspect circuits for each. It helps a beginner build a diagnostic routine before turning to the schematic of the actual device. Use it as orientation, and always confirm with the specific board documentation.
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.