Before going any further it's important to know that modifying the LEDs in your phone WILL void your warranty, thats if it still has a warranty. Modifying LEDs can be dangerous and possibly kill your phone, although this is very unlikely (I take no responsibility for any damage caused to your phone). You should have some ability to solder, keeping in mind these LEDs are very small! With that said lets get going...
The Nokia 7110, waiting to be modded.
For opening any Nokia phone you need a T6 Torx screwdriver. You really must have one of these to do any phone modding, they are available on Shop4Facias aswell as many other places. So the first step is to remove all the T6 screws from the phone and lift away the housing. As a quick note, always watch out for any bits falling out they normally fit back in easily but it can be a nightmare if you drop something!.This will vary depending on what type of phone your modding but in general its not too hard, just look for the little screws (usually located under the battery) and remove them. Be very careful when removing screws inside the phone - one slip and you could be in trouble. Also try and avoid a T6 screwdriver that is magnetic tipped because it may affect the phones sensitive electronics.
Above: The four T6 screws (marked in red), other models may have more/less
Below: My T6 screwdriver and the screws removed.
Once the screws and the housing is removed you should be able to separate the phone into a number of pieces. Again it's so easy to lose something so make sure you have a nice clean workspace and a relatively tidy environment. The aim of dismantling the phone is to access the LEDs in both the LCD and the keypad.
Below: Housing removed to reveal the phones main PCB
We still have not reached the phones LEDs so yet more dismantling is required. Remember the LEDs in different models of phone are located in different places, this being a general guide I will only point out the LEDs found in the 7110. If your modding a different type of phone there are more specific guides available on the internet, detailing the exact location of these LEDs. Saying that, with any luck you should be able to identify the LEDs in your phone just by browsing the PCB.
Above: Jackpot, at last some LEDs! These are the keypad LEDs, notice how small they are.
Below: A closeup of the six LEDs, you can just about work out that these are sideways facing.
We might have found some LEDs but the dismantling isn't finished yet. If your planning to fit LCD display LEDs then continue removing pieces of the phone until you reach the LCD module. Keep in mind all the time that you need to reassemble the phone after modding. Hint make a note of how it all fits together, even if it is just a mental note. The module should now lift out. If you cock up this mod you can usually buy another LCD- again Shop4Facias sell them. To fit keypad LEDs apply the same methods as explained in the LCD LEDs below, ensuring the LEDs are the right way around (see polarity diagram, they do not need to be sideways facing)
Above: The LCD module on the left and the phone PCB on the right.
Below: The single LCD module