1. Try getting any logs from XS++, SeTool2 Lite, jdFlasher ...
2. Disassemble your phone. If you get lucky, you'll see any kind of damage already them. Try to replace damaged part. If everything is fine, go to Service Center. You might need to pay :(
3. Try changing battery pack or check if battery pack gives correct output voltage and frequency ...
4. Does your phone has some light indicator or something like that? For example - K610i got really useful diode / indicator on to top side ...
5. Give us a bit more look in previous actions taken - when phone still worked ...