This seems like your "Backlight" is either faulty, or the power supply, or inverter driving it is faulty. This Make & Model isn't very well supported, i have searched the 'net, but have been unable to find a service manual, or any manual, which, one really does need, if only for the part numbers to reorder spares.
In saying that though, there is nothing "Special" about them all. They all use a fairly standard type parts. So if you disassemble, the unit, and locate the backlight, and they have a part number on them, you would be able to get the part, from Ebay, or by contacting the maker of the backlight directly. You really need to check the voltage is coming out of the driver, and it actually the lamp itself. But as I said before one really needs a service manual to be able to do that.
http://hackaday.com/2005/11/01/lcd-backlight-replacement/
Have a look at this tutorial above.