I would suspect the inverter, as it is a known point of weakness in all these screens. I have a 17" ADC screen in which I initially thought the trouble was the backlight. Turned out to be the inverter.

Replacements for the failed rectangular components on these boards must be available somewhere, one would think. I fixed my 17" by sourcing an inverter board from a replacement screen with broken plastics, but I remember thinking at the time that it would be a reasonably simple soldering job to replace the faulty components. I just don't know what to look for or where. If I did, I'd want to source a few spares, just in case. The entire inverter board is hard to find and expensive to buy when found.