I was referring to @Dorian Instructions:
If that helps, I do this to calibrate the ESC:
Remove the propellers
I feed the Air Unit independently of the Cube via an UBEC. I have noticed that there is a delay of a few seconds between the moment the Air Unit is powered up and its operation. You have to do this to tell the Cube that you want to calibrate the ESC.
1 Switch on the Herelink
2 Supply the Air Unit
3 Hold the HL throttle stick at the top
4 Power the Cube so that it enters ESC calibration mode
5 Disconnect the power from the Cube
6 You can put the Air Unit, Cube and ESC on the same power supply
7 Always keep the HL throttle at the top
8 Connect the drone battery (Air Unit, Cube and ESC)
9 Wait for the Air Unit LED to light up
10 Press and hold the security button until it turns solid red
11 ESC must emit music signifying that maximum acceleration has been recorded
12 Pull the throttle stick down and hold it, the ESC emit music indicating that the minimum acceleration has been recorded.
13 Following this, the ESC are active and the motors can run.
14 Disconnect the battery
15 Normally, this should work, otherwise repeat the procedure.
These instructions are good but they could be clearer
- Power the Cube so that it enters ESC calibration mode
This is a bit misleading because the Cube does not go into ESC Calibration mode at step 4. The Cube needs to be powered up with the throttle stick high (Step 4) then have the power removed (Step 5) and then powered back up again with the throttle held high (Step 8) before it goes into ESC Calibration Mode. And after that you still need to get do Steps 9 & 10 before the ESCs begin to calibrate.