Make sure your computer is off. Take your battery pack out and wait two minutes. Put the battery back in and make sure your other power source is plugged in. Turn your computer on and see if that works. My Toshiba had a similar problem and it worked. If it does work, check to make sure you have the latest Bios downloaded. Hope that works for you. Make sure all your power sources are disconnected first.
I forgot to mention that once your battery and other powersources are disconnected, press your power button and then wait two minutes before turning it on. Good Luck!