Hints in troubleshooting keypad LED light failure problem:
1. Check the keypad matrix flex assembly, clean it if oxidized. replace the whole flex board if severely damaged.
2. Check each of the white LED light bulbs using a multimeter set to X1.
3. Check and trace the positive (LED+) and negative (LED-) supply voltage.
3. The negative supply(LED-) of the keypad LED is feed from the PEARLJ IC.
4. The components such as the transistors, inductor coil and diode will only be check if also the Display backlight LED failed or show a dark screen