I have to agree the experience of opening my gunfighter with MCG3 was an extremely disappointing one. First the QR code on the very poor quick start leads to the general YouTube channel where you can't find anything except how to calibrate or flash the MCG III / Gunfighter.
Googling for "vkb sim gunfighter mcg quick start guide" gets you to a PDF for the MK.II. Going further gets you to a forum post from 2020 wherein it says that the guide will be updated (
viewtopic.php?t=3958) - it apparently never was.
This forum post - found an hour later - has a link to a youtube video "Replacing cams and springs, adjusting the dry clutch, installing a grip on a GunFighter base" - you can't see any text after "Replacing cams and springs, adjusting the dry clutch..." in YouTube so there is no way you will find the "installing the grip" bit, even searching YouTube for 'install", "setup" "quick" - which I did.
There is no cabling connection diagram anywhere I have found yet. I'm sure I'll figure it out, but have no idea why I have a box at all, what the LEDs on it are for, and whether my joystick is supposed to go into the S-Bus or the L-Bus (whatever they are).
I bought this thing after having bought my Gladiator EVO NXT which has pretty clear and findable instructions and YouTube Films, so expected a similar experience. Not so, it's been downright painful for the past 1.5 hours now and I'm just hoping that after I connect to the S-Bus and then the USB further the thing will be detected. We will see. Otherwise I'll try the L-Bus. Not impressed so far.