Simulate powerbutton

I want to use terminal task to to turn the screen off using tasker. I have tried a code like this, and some variants, without success. am start --user 0 -a android.intent.extra.KEY_EVENT --es KEYCODE_POWER ACTION_DOWN I have also tinkered with  android.intent.action.SCREEN_OFF  but with even less success. Any ideas as how how I can get this to work? Either with terminal emulator or tasker *send intent* task? Note: Not rooted, som shell task in will not work. And System Lock doesn't work well with finger print reader