You should try this one instead:

(Add-Type '[DllImport("user32.dll")]public static extern int SendMessage(int hWnd, int hMsg, int wParam, int lParam);' -Name a -Pas)::SendMessage(-1,0x0112,0xF170,2)

Or, you can use a Powershell script like this:

Add-Type -TypeDefinition '
using System;
using System.Runtime.InteropServices;
 
namespace Utilities {
   public static class Display
   {
      [DllImport("user32.dll", CharSet = CharSet.Auto)]
      private static extern IntPtr SendMessage(
         IntPtr hWnd,
         UInt32 Msg,
         IntPtr wParam,
         IntPtr lParam
      );
 
      public static void PowerOff ()
      {
         SendMessage(
            (IntPtr)0xffff, // HWND_BROADCAST
            0x0112,         // WM_SYSCOMMAND
            (IntPtr)0xf170, // SC_MONITORPOWER
            (IntPtr)0x0002  // POWER_OFF
         );
      }
   }
}
'

[Utilities.Display]::PowerOff()

Actually i'ts terrible expansive, as a comparison the minimum wage in USA is 7.25 USD (02-2021), while in Brazil is 1.2 USD (02-2021), ~604.16% more. So thinking about it, a fair price would be around 3.3 USD, equivalent of ~16.55% the original value.

The correct structure would be:

Alexa, execute notepad com o parâmetro X.