Replacent nav screen still not working

[The Lexus Enthusiast]

Hi guys, so the good news is that I have a new nav screen. Lex Elleven kindly agreed to sell me his old one. Bad news is it still doesn't solve the issue. I received the screen this morning and have just installed it but very sadly it is behaving same as old screen. Except for the fact the graphics are a bit clearer and there are no lines over the lexus logo at startup. I have looked at the nav disc reader in the boot and it ejects rhe nav disc so I think reader is working? Maybe is the nav disc. Does anyone have the old nav disk lying around? Mine says Europe 'A' version 1 2003-2004? Worst case scenario would anyone have the nav disc reader for sale? Also there is still no reversing camera displayed when I select reverse even with new screen installed. When you press on the map voice and destination buttons I hear the feedback sounds but screen is black like with old screen.

Any ideas guys. Is on my new 2003 facelift. 

Thank you. 

[The Lexus Enthusiast]

The other interesting thing is that there is no cable that goes into the third small square plug? Is this normal that only the two long rectangular plugs are used or is there something amiss with the wiring in the car?