How to dynamically change Text of Button control in GridView RowDataBound event in ASP.Net

Using RowDataBound

HTML:

<form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" OnRowDataBound="GridView_OnRowDataBound">
            <Columns>
                <asp:BoundField DataField="ID" HeaderText="ID" />
                <asp:TemplateField Visible="false">
                    <ItemTemplate>
                        <asp:Label ID="lblIsRead" Text='<%# Eval("IsRead") %>' runat="server" />
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:BoundField DataField="Product" HeaderText="ProdcutName" />
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:Button ID="btnSold" runat="server" />
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
    </div>
    </form>

C#:

protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
                this.PopulateGrid();
            }
        }

        private void PopulateGrid()
        {
            DataTable dt2 = new DataTable();
            dt2.Columns.AddRange(new DataColumn[3]{new DataColumn("ID",typeof(int)),
                                new DataColumn("IsRead",typeof(bool)),
                                new DataColumn("Product",typeof(string))
                               });

            dt2.Rows.Add(1, true, "Mobile");
            dt2.Rows.Add(2, false, "TV");
            dt2.Rows.Add(3, true, "Fridge");
            this.GridView1.DataSource = dt2;
            this.GridView1.DataBind();

        }

        protected void GridView_OnRowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                bool isRead = Convert.ToBoolean((e.Row.Cells[1].FindControl("lblIsRead") as Label).Text);

                (e.Row.Cells[3].FindControl("btnSold") as Button).Text = isRead == true ? "true" : "false";
            }
        }