Inverter
Daughter had the same, 'ghost of an image', the inverter board has most likely gone u/s. If you look on the internet there are instructions on how to replace it. Relatively easy. Hardest part is sourcing the right board: each machine has several variants. Got one from ebay seller and worked fine. Think it cost less than £40. 20 minute job but take your time with the connector. Inverter lives under the plastic strip just above the keyboard.
Unlikely to be backlight (and these are just about irreparable).