Set Mode selection switch with Channel 5. This means rotating the handle VrA can change the flight mode.
Set emergency motor stop with Channel 6. This means you can switch off the motors immediately by turning VrB.
Follow COEX Power setup. Measure the voltage by the voltmeter included by COEX. (The display shows TOTAL voltage → each cell voltage.) This helps QGroundControl to show the correct battery percentage.
For ESC calibration, please disconnect the power cable from PDB to FCU. Connect the USB cable from FCU to laptop. Don't disconnect the battery since this calibration needs the battery to drive the motors.