I have a B850M. It has Q-Flash. Here’s what I did.

1. Format a USB stick to FAT32/16/12 (as per the Q-Flash website), and plugged it into the BIOS-labelled USB port on the motherboard.
2. Download a BIOS version from the motherboard site (look for “Support” and “BIOS”).
3. Copied and extracted it onto the USB stick.
4. Boot into BIOS.
5. Go to the Q-Flash menu.
6. Select the extracted BIOS file from the USB stick.
7. Update.
8. Reboot.

After rebooting, the motherboard’s main decorative LED was lit, but nothing else was happening. There was no display output, and none of the fans were spinning. 10 minutes later, it’s still in the exact same state, so I cut the power and rebooted again. This time, all was well.