Asp.net - C# - Disable button / lock screen after download is complete on the browser

Hi,

I am using xmlwriter to create XML document  from excel, I am able to create XML document and able to provide an option to the user to save the file on their computer.

However when download completes the form is still open and all button are accessible. I would ideally like to disable  the "Btn_Process " btn when the download starts or ends , I have used the option to disable to the button at all stages on click event of the button and also below in the finally statement , but the btn does not get disabled.

I would like any of the following :
1. Disable button Btn_Process on click of the btn or after the download completes
2. Lock screen when downloading is in progress then unlock
3. Redirect to the same page after download is complete

Thanks in Advance

The code is as follows:

try
                {
                    CreateXML(TableA, TableB);   //Call Create XML Method 
                }
                catch (Exception e) { //Ex catch}
                finally
                {
                    Btn_Process.Enabled = false;
                    HttpContext.Current.Response.End();
                    Server.Transfer("Excel2XML.aspx");
                    
                }

The above CreateXML method has the below xmlwriter For creating the XML file :
           

string name = string.Format("attachment; filename=HDCLv1_NYC_{0:yyyyMMddHHmmss}.xml", DateTime.Now);
            HttpContext.Current.Response.ContentType = "application/xml";
            HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;
            HttpContext.Current.Response.BufferOutput = false; 
            HttpContext.Current.Response.AppendHeader("Content-Disposition", name);

 using (XmlWriter writer = XmlWriter.Create(HttpContext.Current.Response.OutputStream, settings)) {  

                writer.Flush();
                writer.Close();
                HttpContext.Current.Response.Flush();