HP Notebook User Manual page 64

If the computer is unresponsive and you are unable to use the preceding shutdown procedures, try
the following emergency procedures in the sequence provided:
To shut down the unresponsive tablet:
Press both the Windows key and the power button at the same time.
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To shut down the unresponsive tablet when it is connected to the keyboard dock:
Press ctrl+alt+delete, click the Power icon, and then select Shut Down.
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Press and hold the power button for at least 5 seconds.
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Disconnect the computer from external power.
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54 Chapter 6 Managing power