Lenovo Windows executable carrying the BIOS update with version code JKCN53WW, roughly 8.5 MB. The name does not state the laptop model, so confirm compatibility from Lenovo's support listing for that BIOS family before running it. Besides normal flashing under Windows, technicians often unpack such installers with 7-Zip or vendor switches to pull out the raw firmware for programmer use. Keep the battery charged and the adapter connected while updating, and make a backup dump of the SPI chip first if recovery might be needed.
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 @dtechbios. Enginerys does not host this file.