You're kidding me. That's it?!? Wow. Yesterday I was so frustrated asking for help from Minisforum I ordered a new PC off Amazon. (Asus Expertcenter.)
So the steps are --
1. Download the BIOS.rar
2. Decompress and put folder on desktop
3. Inside that folder right click FLASHWIN.exe and select OPEN.
4. Allow program a minute or so to run and then it will automatically reboot.
(I added extra details above to confirm exactly what you said.)