If your board have Q-Flash Plus (PLUS specifically!) functionality you can try to do it through it. There should be button on motherboard and USB that is written Q-Flash above it. Put BIOS image on USB (as single and only file that will be on drive). USB should be FAT32 formatted. BIOS image should also have specific name which you can look in motherboard instruction on Gigabyte or Aorus support page.
Put USB in that specific port then press Q-Flash Plus button on motherboard. Tbh never done that, so you may look for better explanation of it on Youtube or other forums.
UPD: tried to look up. If i get on right MB through "Aorus B450M" search it have Dual BIOS but only simple Q-Flash (funny, my B550M have 1 BIOS, but do have Q-Flash Plus). So... Good luck with boot kit, i guess