Here's simple solution that might help to solve and fix nokia 5630 ON and OFF key failure. If the device show charging indication when the battery microusb charger is plug-in but won;t power up when the power key is press. This solution shows some components and line paths of the power key that might caused the problem.
Nokia 5630 ON-OFF/End call key solution (power key jumper ways)
You can use this solution guide to trace the power key line tracks from the keypad membrane matrix down to the pin connector and particular certain components that might get damaged. In the solution above, there are components composed of a SMD capacitor and an ESD filter chip, you may check these particular components also and replace if found faulty.