2000 - screen illumination - motorprop

This car has a screen displaying navigation / radio settings . It works well, but just now it has started to play up : After initially being well lit as usual at the start of each drive, the screen becomes blank after about 5 minutes, though the radio continues to operate normally, channels can be changed etc. It then comes on sporadically . This sounds like an obvious loose contact , but where is it ? When blank, looked on from a certain angle , you can see the display faintly , but there is obviously a fault that has just manifested itself .

any advice gratefully considered - also , Mitsubishi want about £125 for an updated Navteq navigation disc , with the original being a 2000 vintage . I do have a portable sat nav , but the built - in one is more reliable . Navteq refers you to the dealers . That is too much IMHO to pay for a mapped CD . Any ideas of where to get it cheaper ?