Range Rover L322 Head Unit Not Working

We have had some issues for the last two years with the sound system in our ranger rover Vogue 322. At the moment it hasnt been working and something has been draining the battery. We took out fuse 8 and 49 from the board (for the head unit and computer) and it seems to have stopped the battery draining.

We've changed the head unit today and reinserted the fuses and when we turned the ignition on the screen went to black, but nothing came on it! The orange light next to the power button on the radio didnt come on either. We think it might be something to do with the electronics in the boot of the car but its so complex we could really do with some help to try and diagnose the issue! Any help would be much appreciated!

Easiest way to help you, is to send you to the search bar. There are lots of threads on the issues with the stereo and water ingress. Just type in something along the lines of 'L322 stereo water ingress', or similar.

Addit: loads on battery drain too , but probably a different search.