Checkbox value always returns true, Google script HTML service

I have created a google sheets sidebar using the google script HTML service which has various text boxes and checkboxes. i have no problem passing the variables through to the google script. The problem i have is that the value of my checkbox is always true or "Y" in my case whether is is checked or not. I really would like to know how to set the value as "Y" or "N". I wont upload complete script just the important bits because they are quite long.

This is my checkbox within my sidebar HTML...

</div>
<div class="block form-group" id="Headset"> 
<label for="headset-Check">Headset?:</label><br>
<input id= "headset-Check" type="checkbox"  value="Y"> 
</div>

this is my javascript calling various google script functions the bit that uses the checkbox is near the bottom,

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">             </script>
<script>

 $(function() {
 // Assign handler functions to sidebar elements here, if needed.
 $('#GetSerial-button').click(onGetSerialClick);
 $('#Submit-button').click(onSubmitClick);
 });


 function onGetSerialClick() {
  this.disabled = true;


   google.script.run
      .withSuccessHandler(
      function(msg, element) {

        $('#Serial-value').val(msg);
        showStatus('Pulled Serial Successfully.');
        element.disabled = false;
      })

    .withUserObject(this)
    .getSerialValue();
 }


 function onSubmitClick() {
  this.disabled = true;

var serial = $('#Serial-value').val();
var warrantyNotes = $('#warrantyNotes-value').val();
var warrantyRepair = $('#Warranty-Repair').val();
var headsetCheck = $('#headset-Check').val();


    google.script.run
    .withSuccessHandler(
      function(msg, element) {

        showStatus('Submitted ');
        element.disabled = false;
      })

    .withUserObject(this)
    .setHeadsetValues(warrantyRepair,headsetCheck,warrantyNotes,serial)
    google.script.run      
    .addNewRow(); 

  }

 function showStatus(msg, classId) {
  $('#sidebar-status').removeClass().html(msg);
  if (classId) {
  $('#sidebar-status').addClass(classId);
  }
  }

i then have a GS function to put the variables into correct sheet.