What LED's display when CM3 IO Board is powered

I have a new CM3 plugged into a CM3 IO Board.
I have plugged the power in but none of the LED’s illuminate.
How do I know if the board is working or faulty?
Thanks James

what’s you cm3 mode, does it have emmc on the board, if not ,you should boot from sdcard, About how to install image on sdcard,you can refer to