Make sure your laptop is turned on and that the battery is charged. If the laptop has frozen, try pressing the power button to see if it will shut down on it's own. If the laptop screen does not turn off, press and hold the power button for at least 20 seconds.
You should check the power supply for damage. If you see any physical damage, you’ll need to replace the power supply. If you don’t see any damage, try to reset the system by pressing the power button and down volume key at the same time for 10 seconds.
In the unlikely event that your device becomes unresponsive, try a force reboot. Press and hold the power key for up to 30 seconds to perform a force reboot on the device. Tip: If reboot was not successful you should attempt the reboot while connected to a wall charger.From the "No Command" screen (Android figure lying on his back), press and hold the Power button then press and release the Volume Up button to display the menu options