a solution for Nokia 5630 Xpressmusic LCD Display LED back light problem that shows a dark screen display due to the LED's failure to illuminate at the back of the LCD screen display module.
If this problem happens and trying to fix the device, you may first try to replace the LCD module, to easily determine if the white LED's mounted at back of it is already been damaged or not.
If after installing a new LCD but still it shows a dark screen display, you may then refer to the solution below and locate those certain components for check up and for tracing the display backlight LED's connection line paths.
Nokia 5630 LCD Display Back light Solution
Find all the components showed on the solution above on the device PCB board, and then check for possible damaged and then replace it. The filter coil is connected to the battery positive supply voltage of 3.7 volts, if this voltage is missing just mend to reconnect it through to the battery's B+ terminal or other components such as the supply voltage big filter capacitor.
Trace each of the LED's connection line paths from the LCD pin connector down to where it is being connected in a certain capacitors components.
Since only the LED's positive supply voltage have a ideal spots where you can check it connection line path.
While the LED's negative supply voltage is connected directly to the GAZOO chip, so there's no way out that you can check its connection down to the solder ball of the chip.
You may tend to rework the GAZOO chip if the LED's positive supply is working ok and if the problem still exists.