Connecting to the serial console
The NavQPlus kit comes with an FTDI type USB-C to UART adapter cable and a small adapter board for this cable to the serial port JST-GH connector . This adapter is used for a serial debugging console on the NavQPlus.
Executive Summary: Connect the included USB to UART adapter to the UART2 port on the NavQPlus, and open your favorite serial console application (e.g. PuTTy for Windows users, Minicom on Linux). Open a serial console and set the baud rate to 115200. If there is no output on the screen, try to press enter to get a log-in prompt.
Connect USB cable+ adapter to your computer. Then plug in the JST-GH connector from the adapter into UART2 (A53 Debug/Console) port on NavQPlus.
Use your favorite serial console software such as PuTTY (Minicom, MobaXTerm, or screen) to access the NavQPlus serial console directly.
The baud rate is 115200.
The serial console may be used to observe the full boot sequence including uboot. BONUS!: The terminal program on your PC should not disconnect on reboot or reset of the NavQPlus since the connection at the PC is really to the USB-UART adapter board (inside the TTL-232R-USB cable).
If correct code was loaded, and the boot switches also set back to the correct boot source (SDCARD vs EMMC), then in the terminal software you should see the Linux boot details printing out.
The system will ask for the username and then the password. The default username/password is as follows:
At this point you can start using Linux on the NavQPlus.
Username: user
Password: user 
How to boot the board
NavQPlus should boot normally after applying power. While booting, the device will output detailed status information to the serial console, accessible on the UART2 connector. Using the console can provide invaluable debugging information that is difficult to find elsewhere. Once the boot process has completed, the system console is also available by starting an SSH session over (USB-)ethernet or Wi-Fi.
There are DIP switches on board that select the boot source as either SD card or on-board eMMC memory. Ensure their settings match your intentions.
If the applied voltage at PWR_IN is too low, the boot process could hang upon initializing the CPU in the Linux kernel. Please make sure that your power input is 5-20V. The NavQPlus has relatively low current requirements and typically will not draw more than 4 watts of power when all on-chip peripherals are enabled, however the board may also supply power to external devices. Ensure that your power source is able to maintain a stable voltage level at the requested current.
If powering from USB-C it is possible with some Linux kernel/boot configurations that the USB-C port hardware is limiting current, or switches modes as software progresses. This may result in a hang or a reboot. If you suspect this is the case, try powering from the PWR_IN port instead.
The boot process starts with U-Boot, loading the device trees in the boot partition and loading the Linux kernel. If you desire to observe the complete boot process, you will need to monitor the output on by using the provided USB to serial converter cable.
Once the NavQPlus has booted to the shell, the default login credentials are as follows:
Username: user Password: user