Recovery files for the Dahua DH-XVR4B16-I 16-channel recorder, in an 86.5 MB ZIP with codes 57_271, 80206979 and D2018 in the name. These likely identify the board version, part number and PCB design. The archive is large enough to hold a full dump or several firmware pieces. Use it to restore a non-booting unit by programming the flash externally. Verify the board marks first, read and save the existing chip, and check that image and chip sizes agree.
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 @laptopchiplevelrepair. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip