Steve,
I did give it a quick try, just before Christmas, but it didn't ask me for a code.
There was a reasonably loud buzzing, (emanating from the door speakers), but it would not respond to any key presses so I couldn't even try the code that I found behind the dash.
Shortly afterwards it occurred to me that I hadn't got the CD Auto Changer connected, (there is a multi pin DIN connector that runs back to the 'head unit'), and it may be that there is some form of 'interlock' that the head unit needs to 'see' before it will behave normally and ask for the code?
When the vehicle was 'delivered' to me I noted that it had a four digit code showing in the display window - which I believe is normal behaviour when an incorrect code has been entered - so I am reasonably confident I will have it up and running sooner rather than later, (famous last words).
I am sure that other, (more knowledgeable), forum members will correct me if my assumptions are incorrect however!
On the 'older' ICE equipment the only real issues were with the output stages, (usually multi channel power amplifier chips), but on later equipment there can be power regulator issues, (usually some form of LM705 5 volt regulator chip), that is used to provide a stabilised 5v logic supply for most logic circuits.
Tape players, (going back to a time when dinosaurs roamed the earth), usually suffer worn/stretched belts, filthy pinch rollers and dirty/worn heads and the CD Auto Changers suffer from the Laser Sled assembly becoming faulty or out of alignment.
Radio and logic circuits are usually very reliable.
I have spent most of today preparing the floor panel for repair, removal and cleaning of my auto transmission push rod, (trying to select any gear is very difficult and required a huge amount of effort), and, (whilst in the area), I have removed the inhibitor switch as the previous owner had joined the connector with huge crimp connectors and then wrapped the 'mess' in duct tape - I couldn't leave it like that!
I also repaired about 20 wires, (in the main looms), that had been chewed by the previous Rodent residents by soldering them together and finishing with heat shrink to make a near professional finish.
All of my 'computers' have been removed, (whilst I repair the wiring), including the BCU and that is why I can't retest the radio until later in the week.
I have taken lots of pre/post pictures and hope to document the work on the forum - once she is back together, (and running)!
I haven't even driven this vehicle yet so I don't know what other horrors are lurking within - but I decided to take a gamble to see what all the fuss is about with these Range Rovers and the price was right!
Always happy to assist with any ICE repairs if required and should the need arise.
Apologies to everybody for the long post.