Firmware archive labelled only as Redmibook 15, with no board number, BIOS version or CPU variant in the name. The 6.41 MB ZIP probably contains a BIOS dump for SPI flashing. Because several Redmibook 15 variants exist, open the archive and check the version string inside the image against the original firmware before use. Read and save the existing chip with a programmer before writing. Make sure the image matches the chip size, and verify after programming before reassembling the laptop.
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 @biositechyangiyer. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →