Your bios wont see it because it must fall outside of any naming conventions requirements. The better option is to use the flashback feature on the board. There are many videos showing the flashback being used.
https://www.youtube.com/watch?v=JVvHwq3syqI just one of many.
There are a few basic requirements though.
1. Format the USB stick to fat32. There are manuals stating it works with NTFS but some wont so go for the safe option.
2. The file must be in the root directory
3. For Crossfire VI hero the cap file name is c6h.cap. Rename the bios file to this.
Steps to use it.
1. Switch off the power.
2. Insert the USB stick into the flashback slot. It is a 2.0 slot with the white box highlighting it.
3. Switch the power back on, but do not initiate start up.
4. Press the flashback button and hold for 3 seconds. It will start flashing with a blue light.
5. Do not power off until the blue flashing has ceased.
6. restart the machine with the new bios update installed.