Sorry for the trouble caused to include your original text. In fact, I used large font and different font to make reading easier,
probably it was reformatted after transmission. See attached screenshot for my original text.
Yes, the Pixhawk is a clone. I am aware of this voltage level of Vcc and am not comfortable about it, but thought
it is not too much lower than 5V and may not cause much trouble. Adding capacitor is a good suggestion.
For ESC BEC voltage, since there is no servo connected to output, I should remove the 5V red wires from 3 BEC cable,
leaving 1 BEC to supply +ve voltage to complete the circuit with ground, right ? Pls confirm.
Will replace the relevant connectors to see if Vcc can be raised.
I will also change GPS_GNSS_Mode to 3, see if it works, as my outdated NEO 6M GPS does not support GLONASS. In fact,
my 2 other NEO 6M GPS do not get 3D fix recently. They were working very well 6-9 months ago.