A RAR file of about 953 KB intended for the Xiaomi Mi 5 smartphone. Beyond the model name, nothing indicates its contents, board revision or version, so extract it and check what is inside. Service documents of this size typically consist of schematic pages that a technician reads to follow power-up sequencing, test the charging and battery circuits, and find the parts sitting on a line that measures shorted. Make sure the mainboard markings correspond to the documents before relying on part positions or values.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.