Interpreting your description could mean that everything works except that it is dark. This being the case, then it could be indicative of defective:
- CCF lamp(s) (cold cathode florescent); and or
Depending on the size, there could be two or more lamps. The lamps provide the backlight
similar to the LCD panel display of a cellphone. These lamps are powered by a high voltage/high frequency board called the inverter.
This of course would require a fair familiarity of electronic components/circuitry and safety procedures, use of a DVM and a soldering iron. It would be to your added advantage access to a service manual or at the very least a schematic diagram with voltage readings. Should you be uncomfortable performing a DIY (do-it-yourself), perhaps your best bet would then be to seek the services of a qualified professional.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.
Good luck and kind regards. Thank you for using FixYa.