GSM Learning solution

Heres a solution for Nokia N97 backlight LED on the QWERTY keys not working or failed to light up.
This solution can be used if the keypad membrane flex is not damaged but the LED backlight still wont light up.
The solution above shows the qwerty keypad backlight LED circuit, it is composed of LED driver IC and filtering Resistors. These Resistors has a 0 ohms resistance value, you may check first these resistors before troubleshooting  further.
The LED driver needs the Battery Voltage which is 3.7 volts that came across with red color highlighted component Resistor, check that voltage and continuity to the battery B+ terminal.
If all the Resistors were okay, you may then proceed to check or replace the LED Driver IC.

This solution shows the camera module circuit of nokia 2710 navigation edition. If the camera failed to initiate, this solution might help fix and repair the problem. If already tried to restore its firmware but the problem still exists, this solution shows the tracks of the Camera module supply voltages that needs to check before attempting to replace the camera module assembly.
There are three power supply voltages that makes the camera module works and operate if one of these voltage were missing the camera  will not function, and it shows camera hardware failure, camera on standby and either no reactions or indication at all.
A Camera on standby mode may fix by restoring its firmware. If an empty or black Lcd showed on the LCD display Lcd,  the problem may lies on the camera module itself, replacing it will possibly solve the problem. So first ensure that the firmware is secured before proceeding to hardware troubleshooting.