PX4 Autopilot
If you are using PX4 Autopilot, please refer to the PX4 user guide page for additional information.
https://docs.px4.io/main/en/flight_controller/pixhawk6c.html
https://docs.px4.io/main/en/assembly/quick_start_pixhawk6c.html

Ardupilot
If you are using PX4 Autopilot, please refer to the PX4 user guide page for additional information.
https://ardupilot.org/copter/docs/common-holybro-pixhawk6C.html