Domino Qi Serial
As the UART of OpenWrt is connected to AVR, you have to use the serial console via AVR.
Connect Domino Qi Mini to your computer. Don't use the MicroUSB connector in the Qi baseboard (There are footprint, but we don't solder it by default).
When you got your Domino Qi for the first time, it may already have flashed the serial terminal to AVR. If not, do it now.
The instructions of how to use this is documented here: https://www.arduino.cc/en/Tutorial/YunSerialTerminal
If you use Linux hosts, you may likely have the devices identified as
/dev/ttyACM0, connect to it using kermit.
If you are using Windows system, you may have device identified as
Arduino Yun, find its port number and connect it to using