if the motherboard is a few years old a lot of motherboard vendor built a bios update tool into there bios. all you need is a unzipped bios file and a usb stick. some of the asus mb have usb flashback ports...all need is a usb stick and bios file. with standby power you press a button and your done. on older mb you have to make a dos boot usb stick and use award or ami bios updater and the bios file. most time you in dos would type award.exe name of the bios file and / to save the old bios file to the usb stick. the program would run from dos and you be done.
https://www.youtube.com/watch?v=LGKNuLCEM4Y