Just leaving this here incase it helps anyone else.

Needed to update a recently bought ASUS ROG Crosshair VIII Hero X570 (non-wifi) to be able to use x5000 series CPUs.

First few attempts after following directions to put properly renamed via biosrenamer.exe .CAP file on USB were unsuccessful and produced a solid blue light after holding down the bios flashback button for three seconds/three blue blinks. (note: no cpu or ram attached to the board)

What ended up making it work was needing to do a bit more of an involved format job, windows device format alone wasn't effectively automatically reducing the USB to a single partition. This is actually a pretty critical step to ensure the motherboard reads the usb stick.

Not entirely necessary to format to FAT16, but that's what I tried at first. To do so, I used diskpart to remove the extra partition that was appearing, and also ensuring a single partion remained of size 4000 on it (command for this using diskpart with the proper partition and disk selected: "create part primary size=4000"). and then, going back to windows right-click format tool, formatted to FAT16 (also just called FAT) ensuring a single partition of size 4000 on it.

Just a possible solution to try for anyone else who has been frustrated by this.

Help me im about to smash this fucking motherboard to pieces its an ASUS x570 ROG STRIX F GAMING. Ive been trying for about 7 hours to flash my bios something ASUS claims take 5 mins using their flashback button. Well every single avenue ive tried I get 3 green flashes followed by a solid green light. Ive formatted my usb stick and set to FAT32. Ive tried windows and Bootice so far to no avail. Ive tried multiple USB sticks and it appears whatever has gone on my first USB stick I tried has been killed. Ive cleared the CMOS and tried again. Ive triple checked im downloading the right bios thats compatible with my motherboard after seeing someone else have this trouble. Ive tried with just the motherboard connected to the PSU, ive tried it as a full system with the new 5600x with the RAM and everything plugged in asif it was a working PC. Im at a complete loss, wait months for my new stuff to arrive for this shit to happen. Please please please can anyone offer any advice

Trying to update the BIOS, watched the tutorial on the ASUS website. LED is supposed to turn off when update is finished, but it been on for over an hour. Wondering if it usually takes this long. Video said not to power off computer, remove flash drive, or press reset cmos button.