I have a 2008 Range Rover Vogue SE which since purchase the orange light on the head unit flashes but it doesnt actually turn on. I have read dozens of sites which state the bluetooth unit is the cause but i can say with certainty it is not the cause of the issue. I tried the bypass loop to no avail. Owning 2 other models of exactly the same spec i decided to swap out bluetooth module with one i know works perfectly but it still didnt work but the one i removed from my car with the issue worked in my other car. I then removed all the electronic boxes from the rear & even the sub & swapped everything over from my other car which i know works perfectly but again to no avail, yet everything from the car where the radio doesnt work, worked perfectly in my other car so clearly it was none of the electronics. I even found a thread relating to fuses in the rear but all have been checked & are perfect. Then i found something about a relay in the rear so i swapped this over but still nothing. I havent checked every fuse in the front but i have checked & even replaced the ones people seem to suggest control the infotainment system (even though different threads state its different fuses). Then i found a thread which said press a button then enter a code which apparently at least gives you access to all the function screens, which it did. I can do such & see the preset radio stations etc but there is no sound & when turn ignition off & on again the system has reset to nothing displayed on screen & orange light flashes. Can anyone please point me in the direction of the cause of this headache? Thank you!

I had a very similar issue to yours with my 2012 L322 Vogue SE. I detailed my issues including some pictures in this tread:
https://www.fullfatrr.com/forum/topic62180.html

I've finally managed to get it sorted and it turned out to be the amplifier in the boot area somewhere which was damaged as a result of water getting into where it shouldn't (but apperently it frequently does!). I've paid a wallet rapingly large amount for a brand new amplifier but you could get a second hand one from the usual sites, or I have also seen descriptions of how to bypass the amp. That might be worth a try too.

Thank you for the info, however everything in the boot was swapped over from one of my other TDV8 but the same symptoms persist & all the equipment i removed from the one which the head unit only flashes orange light worked perfectly in my other car. There dont seem to be any reports i can find anywhere of head units going faulty but looks like im going to have to try such as it wasnt any of the 5 boxes in the boot or the amp that are causing the issue