Circuit diagram for the Dell Inspiron 5420, mainboard DA0R08MB6E2 at revision E2, which follows Quanta numbering since Quanta designed the board. Supplied as a RAR of roughly 1.4 MB, it lets a technician follow the power sequence, trace the charger and system rails, and check signal paths around the CPU, memory and EC. The schematic is usually a PDF readable in any viewer. Verify that the silkscreen on your PCB reads DA0R08MB6E2 rev E2, because component values and placement can differ on other revisions.
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 @laptexdna. 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.