Fixing a cell phone is basically not a difficult thing. All you need is proper equipment, basic knowledge of electronics and of course a manual guide, including schematic diagrams. Nokia is one of the largest mobile phone manufacturer in the world. The products are very diverse, lots of types of nokia available in the market.
If you are a cellular telephone repairman, then you should have a service manual guide as complete as possible.
I’ve found a complete Nokia wiring diagram at 4shared.com. The files has been shared by someone there.
Here the links. There are divided in 2 zip parts. Use winrar to extract the files.
» Nokia wiring diagram part 1
» Nokia wiring diagram part 2
Note: I’m not responsible about the file, about the risk or another broken/damage caused. Use the files for your own risk.