RNS-E screen went black, came back the next day, went away - then cam back dim - then black for good.

Using a flashlight I can see that the screen is still active very, very dimly. Unit works fine though and switching modes changes the display (using flashlight)

Have researched that it could be a power inverter or the ribbon? - or the backlight in the screen - would appreciate and expert knowledge to help me narrow it down before I start buying new parts.

Thanks for your help in advance.