Note this solution only works if: you already confirmed that the LCD is ok or tried replacing it. Already check or replace the flex ribbon cable wire but he problem still exists.
Just refer to the given solution below an do have a check and replacement procedures on some components on Nokia X5-01 PCB board.
Nokia X5-01 Display Light Problem Solution
Hints for repair:
- Visually check the flex connector, if oxidized, clean it.
- Check the 3.8V battery voltage across the filter coil. Check/replace also the coil.
- Trace the LED+and LED - connection line paths from the flex connector down to the capacitor and resistor where it is connected.
- Replace the Display LED Driver IC.