Dell LCD Problems

The LCD on my Dell laptop does not have any illuminance. The laptop works fine when connected to an external monitor, so I know it’s not the video card. If I view the LCD in bright light I can faintly see outlines of the desktop. This points to a backlight problem. My question is, do I need to buy a whole new LCD? Or may this be a problem with the inverter? How can I tell?

Any other relevant info would be appreciated. Thanks!