If the computer is not turned off properly due to a system error, press <Ctrl>+<Alt>+<Delete>. When [Windows Task Manager] dialog box appears, click Shut Down > Turn Off to turn off the computer. Your unsaved work may be lost/damaged.
If <Ctrl>+<Alt>+<Delete> keys do not operate either, press the power button for more than 4 seconds to turn off the computer. Your unsaved work may be lost/damaged. When you turn on the computer next time, it will perform a disk checking process.