HP Compaq Presario,Presario CQ40-600 User Manual page 81

If the computer is unresponsive and you are unable to use the preceding shut down procedures, try the
following emergency procedures in the sequence provided:
●
Press ctrl+alt+delete, and then click the Power button.
●
Press and hold the power button for at least 5 seconds.
●
Disconnect the computer from external power, and then remove the battery.
Shutting down the computer 71