Unfortunately, I dont think your motherboard has the BIOS flash feature so you will need a previous generation cpu in order to do it. Do you have a ryzen 2000/3000 series cpu? If you do, you will need to swap out the 5800X and use the 2000/3000 cpu. This is your motherboards support page,
B450 AORUS PRO WIFI (rev. 1.x) Support | Motherboard - GIGABYTE Global , you need at least version F60 to run the 5800X and a usb stick. If you have never updated a BIOS before, watch as many videos as you can until you are comfortable with the procedure as doing it wrong can brick your motherboard. Failing that, if you feel it is something you cant do yourself, take your system to a PC shop and let them do it for you.