You can turn off screen by overriding system screen turn off time.
First get system turn off time
int defaultTurnOffTime = Settings.System.getInt(getContentResolver(),Settings.System.SCREEN_OFF_TIMEOUT, 60000);
then put your turn off time
Settings.System.putInt(getContentResolver(),Settings.System.SCREEN_OFF_TIMEOUT, 1000);
and when the screen turned off, set default turn off time
Settings.System.putInt(getContentResolver(),Settings.System.SCREEN_OFF_TIMEOUT, defaultTurnOffTime);
add below permission
<uses-permission android:name="android.permission.WRITE_SETTINGS"/>