Richie - you have missed the navi calculator (main unit) hidden behind glove box.
This above radio is control module, tmc received and central communication unit (it receives signals about doors, lights, belt, temperature, radio and sends to navigation unit).
You can make a simple test.
If you are sure that you navi screen is ok then press many times quickly Eject button on navi unit in the glove box.
If nothing is shown on screen than you navi module is 100% dead.
It should show renault logo or temperature and time on the screen.
Even if connected only to power supply and screen, without car and control module.
If not then it is dead. (after weak or disconnected battery or failed software update). It can load and unload cds and rotate them every few minutes but if it is damaged, nothing more will appear).
Is there a way to chek that the screen is working or not?