Firstly, I would like to thank you for sharing the amazing job you are doing with this console.
Secondly, I've tried flashing the image on several different microSD cards (including the same 8GB Sandisk you used) and after insert them into the FC3000 and turn it on I get a black screen. I used Balena Etcher and Win32 Disk Imager under windows 10 64bits.
Finally, I don't know if I need to use a linux distro to flash the SD or if I'm missing any steep or boot installation. I 'd really appreciate if you could please give me a hand with this.
UPDATE: After messing around with different cards I decided to try a different card reader. This time it worked! I was able to upgrade my V1 firmware to V2! It seems the card reader I was using first time started to fail and finally died in action (That why I tried a new one).
I used a Sandisk Ultra Micro SDHC I class 10 8GB, the one in red and grey. I flashed it with Win32 Disk Imager under windows 10 64bits and no problems.
Now I just need to figure out what the heck are the .WST files for SNK emulator.
And again, thank you very much for your work Steward_Fu.