如何在面板数组中更改特定的面板颜色?

见下面的代码:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication13
{
    public partial class Form1 : Form
    {
        Panel[,] _chessBoardPanels = null;
        public Form1()
        {
            InitializeComponent();
            const int tileSize = 50;
            const int gridSize = 8;
            var clr1 = Color.Black;
            var clr2 = Color.White;
            // initialize the "chess board"
            _chessBoardPanels = new Panel[gridSize, gridSize];
            // double for loop to handle all rows and columns
            for (var n = 0; n < gridSize; n++)
            {
                for (var m = 0; m < gridSize; m++)
                {
                    // create new Panel control which will be one 
                    // chess board tile
                    var newPanel = new Panel
                    {
                        Size = new Size(tileSize, tileSize),
                        Location = new Point(tileSize * n, tileSize * m)
                    };
                    // add to Form's Controls so that they show up
                    Controls.Add(newPanel);
                    // add to our 2d array of panels for future use
                    _chessBoardPanels[n, m] = newPanel;
                    // color the backgrounds
                    if (n % 2 == 0)
                        newPanel.BackColor = m % 2 != 0 ? clr1 : clr2;
                    else
                        newPanel.BackColor = m % 2 != 0 ? clr2 : clr1;
                }
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {
                int[] x = new int[] { 1, 5, 6, 7, 3, 0, 2 };
                for (int i = 0; i < 8; i++)
                {
                    switch (i)
                    {
                        case 1:
                            {
                                _chessBoardPanels[x[i], i].BackColor  = Color.Red;
                                break;
                            }
                    }
                }
        }
    }
}