This is a result of many hours fiddling about, using multimeters and spare batteries, modifying settings, reading forums and asking questions.

Ultimately, very easy to do.

I take no responsibility for your outcomes. This worked for me, but your setup may be different.

1. open glove box and pry out trim with a plastic tool, starting at the bottom
500X_HU01.jpg


2. using fingers, pull trim piece off, this is what the clips look like
500X_HU03.jpg


3. if you disconnect this connector, there will be a seatbelt error, so don't; just let it hang there
500X_HU02.jpg


4. undo 2 T20 torx screws holding the fascia
500X_HU05.jpg


5. pull fascia out using your fingers, there are 4 metal bolts which clip in quite tightly
500X_HU07.jpg

500X_HU06.jpg


6. undo 4 T20 torx screws holding head unit (red arrow shows lower right screw)
500X_HU08.jpg


7. pull out the connectors, the largest has a hinge clip
500X_HU09.jpg


500X_HU10.jpg


8. transfer metal bolts from factory fascia to new head unit surround
500X_HU11.jpg


9. now for the factory reverse camera hook up
my factory harness looks like this
500X_HU12.jpg


10. make sure the connector on the head unit has the following:
red on pin 31 = reverse camera signal = grey/black wire above
black on pin 32 = reverse camera return = grey/brown wire above
grey on pin 33 = reverse camera shield = black wire above (not sure if this is required)
20220102_reverse camera2.jpg


NB: the connector on my new android head unit (shown below) did not have inputs on pins 31-33, so I added these in by cutting out an audio input from a different part of the connector and transferring the pins across
500X_HU13.jpg

sorry, grey shield is actually pin 33 (not 34 as shown above)

11. from here, its easy, plug everything in, don't forget the can bus box, rout the USB cables (eg I put mine under the soft foam under steering wheel)
500X_HU14.jpg


12. run the antennas for WiFi, 4G and GPS under the dashboard (there's loads of space) and secure the new head unit with torx T20 screws

13. at this stage I had no reverse image, but with perseverance I found reverse camera settings, made them like this:
500X_HU15.jpg


14. and now ...... have reverse camera view!
500X_HU18.jpg


15. set up the launcher of your choice (FCC launcher has split screen option to show SatNav but needs a music player eg musicolet) CarWebGuru laucher has integrated music player and is way easier to setup
500X_HU17.jpg


16. go and enjoy that beer

500X_HU19.jpg


17. And yes, the lines adjust as you reverse and turn steering wheel
steering wheel buttons work (phone, volume, track)
forgot to test the cruise control, will update