the lamps at the top of the screen are probably defective. I have seen the price of these CCFL lamps and they are a little expensive. Another alternative that people are using would be to remove the lamps and put the kit of LED bars and on Aliexpress you have this kit to sell according to the link: s.click.aliexpress.com/e/_et4rLZ
   
Is there another possibility? Do you have an example circuit (schematic diagram) of this board that powers the LEDs?

Here is the circuit and signal lines (VIN,ENA,GND).




СКАЧАТЬ Samsung Monitor TFT-LCD T220 T220G T220N T220GN T200 T200G T200N T200GN: Samsung Monitor TFT-LCD T220 T220G T220N T220GN T200 T200G T200N T200GN.pdf

it is very likely to be a defect in the lamps because at the beginning the image appears and then the screen darkens but at the bottom the image appears very weak.

the voltage on pin 8 of the CN600 connector (BL_EN) is 2.5v
the voltage on pin 2 of the CN600 connector is + 14v

try