Nokia 2630 No network service solution
Ensure that the device firmware is okay or successfully restored or flashed.
Try to upgrade into higher version and write a good PM files.
IF the firmware calibration already done but seems nothing happens you may proceed to trace, check or replace the corresponding components showed on the solution above. Make sure that the PCB board condition is still stable and not like bended or some damaged spots. Check also if there is oxidation build up, clean it first before you may proceed.
First check the PA supply voltage, this voltage is came from the battery B+ terminal and you can trace it between capacitors showed on the solution above.
If the voltage line paths is okay, try to replaced the PA (power amplifier).
Then if nothing happens, you may then try to rework or replaced the RF transceiver chip.
If all the chip is already been replaced but the problem still exists, try to replace the voltage controlled clock crystal oscillator.