Cannot boot from USB

Hi guys,
I’m using a VIM 3. I installed Ubuntu on MMC in upgrade mode flashing from PC.

Now i downloaded an SD image and flash it on USB drive but I can’t start from it.

I press function key 3 times, vim3 restarts, blink blue led, but starts Ubuntu.

Can you help me?

Which image you flash to the USB storage?

HI, thanks for the reply. I have tried ubuntu server and batocera and from usb it not starts.

Today I have tried from micro-sd and ubuntu starts. But not batocera.