Show (Display) Bootstrap modal popup on Page Load from code behind in ASP.Net using C#

I am trying to make popup when a page loads but its not working here is what I tried

HTML

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css" integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2" crossorigin="anonymous" />
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" />
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css" integrity="sha384-9gVQ4dYFwwWSjIDZnLEWnxCjeSWFphJiwGPXr1jddIhOegiu1FwO5qRGvFXOdJZ4" crossorigin="anonymous" />
<asp:ScriptManager ID="script" runat="server"></asp:ScriptManager>
<div>
    <button type="button" id="ballotbtn" class="btn btn-primary" data-toggle="modal" data-target="#MyPopup" style="font-family: Roboto; font-size: 13pt;">Add Ballot</button>
    <button type="button" id="button1" class="btn btn-primary" data-toggle="modal" data-target="#MyPopup">Get Started Here</button>
    <div id="MyPopup" class="modal fade" role="dialog">
        <div class="modal-dialog">
            <div class="modal-content">
                <div class="modal-body">
                </div>
                <div class="modal-footer">
                    <asp:Button ID="newvoter" runat="server" CssClass="btn btn-success navbar-btn" Text="New Voter" Font-Size="10pt" Font-Names="Varela Round" />
                    <button type="button" class="btn btn-primary" data-dismiss="modal" style="font-size: 10pt;">Close</button>
               </div>
           </div>
       </div>
   </div>
</div>

Javascript

<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js" integrity="sha384-cs/chFZiN24E4KMATLdqdvsezGxaGsi4hLGOzlXwp5UZB1LY//20VyM2taTB4QvJ" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js" integrity="sha384-uefMccjFJAIv6A+rW+L4AHf99KvxDjWSu1z9VI8SKNVmz4sk7buKt/6v9KI65qnm" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/malihu-custom-scrollbar-plugin/3.1.5/jquery.mCustomScrollbar.concat.min.js"></script>
<script type="text/javascript" src="jquery.higlighted-5.js"></script>
<script src="js/bootstrap.js"></script>
<script src="js/bootstrap.min.js"></script>
<script type="text/javascript">
    function ShowPopup(title, body) {
        $("#MyPopup .modal-title").html(title);
        $("#MyPopup .modal-body").html(body);
        $("#MyPopup").modal("show");
    };
</script>

C#

protected void Page_Load(object sender, EventArgs e)
{
    string title = "Greetings";
    string body = "Welcome tp ballot";
    ClientScript.RegisterStartupScript(this.GetType(), "Popup", "ShowPopup('" + title + "', '" + body + "' );", true);
}