An archive of repair files for Dell hardware. Shared as “DELL_3421_screen_dark_screen_backlight_does_not_light_up_maintenance.rar” — a .rar file, 447 KB.
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 @bartonarquivos. 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.
7-ZipWinRARThe Unarchiver (macOS)