Cable not fitting behind stock unit

[B3rt]

Today i tried to install my xtrons unit into my Audi A6 C7.5 (mib2) XTRONS 12.3 ''Android 14 Octa Core 4 + 64 GB IPS Autoradio Voor Audi A6 S6 RS6
I need to disconnect the quad block out of the unit and then fit the replacement xtrons cable instead and connect the original quad lock into the stock unit again.

Then the unit should go back in the dash with the cables behind....

Here is the problem, there is simply NO SPACE to fit the extra quadlock cable behind the unit.
I watched several movies how to install, but all movies have a lot less cables as my car behind the head unit.

All the cables behind my unit are original and in use cables such as FB, DAB+, GPS, Mobile etc and then the quadlock and cables to the original screen...
The replacement quad cable is not very long and very stiff it is very hard to bend, so the head unit simply has not enough space to go fully back into the dash..

What can I do about this?