Small 60.5 KB archive named ze600kl, a code that matches the naming style of ASUS ZenFone phones, although the name itself does not state the brand or file type. Given the size, it most likely holds a boardview, component layout or a compact diagram rather than full firmware. Open it to see which program it needs; boardview formats are viewed in tools such as OpenBoardView or dedicated paid viewers. Confirm the model code printed on the phone board before relying on it for fault tracing.
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 @schematicslaptop. 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.