Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net.Configuration;
using System.Security.Policy;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace _5112ShutdownRecreation
{
    public partial class Form1 : Form
    {
        int seconds = 30;

        public Form1()
        {
            InitializeComponent();
            timer1.Start();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Environment.Exit(0);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            using (Process process = new Process())
            {
                var psi = new ProcessStartInfo("shutdown", "/s /t 0");
                psi.CreateNoWindow = true;
                psi.UseShellExecute = false;
                Process.Start(psi);
                Environment.Exit(0);
            }
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            seconds = seconds - 1;
            label1.Text = "Windows will shut down in " + seconds.ToString() + " seconds...";
            if (seconds == 0)
            {
                timer1.Stop();
                var psi = new ProcessStartInfo("shutdown", "/s /t 0");
                psi.CreateNoWindow = true;
                psi.UseShellExecute = false;
                Process.Start(psi);
                Environment.Exit(0);
            }
        }
    }
}