Try these solutions from this thread
Here i quoted a section for you
In order to fix your phone, you need to be calm and patient. Make a wrong move and no one will be able to help you.
Method A) First thing to do is determine if you can connect your phone to your computer and open its file-system up. If you can, just replace the files that you messed up with the original files (If you didn't back-up get the files above) and then restart your phone.
Method B) If you cannot access your file-system because your phone is constantly rebooting, the first thing you need to do is turn your phone off. If the on/off button doesn't work, pull the battery out to turn it off (DON'T TURN IT ON). Then connect your phone to your computer (While its off, and it should turn on by itself and go into a charging screen) and see if you can access your phone's file-system, again if you can replace the messed up files, and restart your phone.
Method C) If you STILL can't access your phone file-system, don't fear there's still hope. Some users have reported success using this method, but it may or may not work for you. Try holding all 4 buttons (camera, lock/unlock, and volume rocker) on the side when the phone is starting, see if you can get it to a white screen with information stating "This phone has the IMEI. If you want to make the gang image erase the IMEI," if you see that, connect your phone to your computer and replace the files, then restart.
Method D) If you find that you cannot stay in the gang image screen above, meaning it turns blue/black with error fatal when you connect to the phone, then do this: Remove the SIM card out and turn on the phone. Hopefully you will get the emergency call screen to display (where you can only make 911 calls). Connect to your phone now and replace the files.