X570 Taichi Flashback Fail

I have just purchased an X570 Taichi in anticipation of getting a new Zen 3 processor in a few weeks.
I downloaded the 1.0.8.0 BIOS update from Asrock, unzipped it and renamed it to creative.rom. I put the file onto a FAT32 USB stick and plugged it into the flashback update port after connecting power to the board.

I pressed the update button for 3 seconds, the light flashed about 3 times then stayed green.

A few points to note:
1. I don't have a current AMD processor.
2. The motherboard had no cpu or memory installed when flashing.
3. I followed the instructions in the manual.
4. I tried with a USB3 and a USB2 stick.

Have I got a problem as the manual says the light should go out.

Thanks