First, unplug the ac adapter and remove the batter. Reinstall the battery and plug the ac adapter back in. If that doesn't work try cycling the battery. Unplug the AC adapter, set your battery warning and shut down in Power options of control panel down as low as it will let you, likely 5%, run the battery until the unit shuts off on it's own, plug the adapter back in, restart windows and allow it to charge fully. Also, make sure you have the latest BIOS version installed. Go to the website product page for your model and compare the available BIOS version against the version installed on your unit.