Spanish PDF numbered topic 5 on disassembling mobile terminals, roughly 954 KB, part of a phone repair training series. It does not name a specific handset. Disassembly lessons cover heating and opening the back cover or screen, removing screws and shields, disconnecting the battery first and releasing flex connectors without damage. Since opening methods differ greatly between models, consult a guide for the exact device before applying heat or prying, and keep screws organised by position to avoid board damage on reassembly.
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.