To fix the Samsung Galaxy A52 LCD dark backlight issue, the first step is to replace the display module. This will help determine if the LED backlight on the LCD is still working or has been damaged.
To further diagnose the problem, you can use a multimeter to test the LEDs, being careful not to damage the LCD's bent connector. If the newly installed LCD monitor still shows the same problem and the LED is not lit, you should refer to the solutions listed and locate the relevant components on the PCB board.