Hi.I had the same problem.I removed the charger,then removed the battery and did hard reset.
For hard reset you should hold the Power button till it vibrates.When its starting to vibrate hold the vol. down button and release this when you see an exclamation mark.Now press vol. up button then vol.down then power then vol.down(in the same order).Now your phone will hard reset (removes all files except sd card files).You can quickly see two gears making updates and then the phone works....(hope).just try it out.