Unable to display the required when returning true from the jquery

Remove return false in line 44

If i remove that validation didn't work and the pop up appears and off in a flash. As per my requirement if i select a check box and click on button i need to work out my code in button if not i would like to show alert

Do the following in steps as I say

1. Change the Button btn to a normal HTML Input Button

2. Add the following LinkButton

    <asp:LinkButton ID="lnk" runat="server" OnClick = "btn_Click" style = "display:none"></asp:LinkButton>

3. Now change the jConfirm in the following way

    jConfirm('Can you confirm this?', 'Confirmation Dialog', function (r) {
          if (r == true)
              __doPostBack("lnk", "");
          else
              return false;
      });

 <script type="text/javascript">
        $(document).ready(function () {
            $("#btn").click(function () {
                var inputs = document.getElementsByTagName("input");
                var flag = 0;
                for (var i = 0; i < inputs.length; i++) {
                    if (inputs[i].type == "checkbox") {
                        if (inputs[i].checked) {
                            flag = 1;
                            break;
                        }
                    }
                }
                if (flag == 0) {
                    jAlert('Select One', 'Alert Dialog');
                }
                else {
                    $("#btn").click(function () {
                        var inputs = document.getElementsByTagName("input");
                        var flag = 0;
                        for (var i = 0; i < inputs.length; i++) {
                            if (inputs[i].type == "checkbox") {
                                if (inputs[i].checked) {
                                    flag = 1;
                                    break;
                                }
                            }
                        }
                        if (flag == 0) {
                            jAlert('Select One', 'Alert Dialog');
                            //return false;
                        }
                        else {
                            jConfirm('Can you confirm this?', 'Confirmation Dialog', function (r) {
                                if (r == true)
                                    __doPostBack("btn1", "");
                                else
                                    return false;
                            });
                            //return false;
                        }
                    });
                }
                return false;
            });
        });
    </script>

 <asp:CheckBox ID="chk" runat="server" Text="Check" />
        <asp:CheckBox ID="CheckBox1" runat="server" Text="Check" />
        <input id="btn" type="button" value="Submit" />
        <asp:Button ID="btn1" runat="server" Text="Click" Style="display: none" OnClick="btn_Click" />

Is this corect? But i am not getting the required

I asked you to add linkbutton and not a Button. Check my reply