Issue in checkbox on check or uncheck

(1) When I click on checkbox then modal is open

(2) when scroll bar reaches bottom one button is enabled and click on this button then checkbox is checked

Issue

When I click on checkbox again then checkbox is not unchecked. Its remain checked

Is there way when I click on checkbox first time then modal is open, checkbox is checked on click button and when I click on checkbox second time then modal is not opened, checkbox is unchecked

Here is my jquery code

$(document).ready(function() {
   var status_box = null;

    $('#termsChk').click(function(e){
    e.preventDefault();
    status_box = this;
    if($(this).is(':checked')) {
     $('#termsModal').modal('show');
    } 
 });

    $('#agreeBtn').click(function(){
      $(status_box).prop('checked', !status_box.checked);
    });

     $("#termsModal").modal({
        show: false,
        backdrop: 'static'
    });
 });

HTML code

       <div class="form-check form-check-radios">
               <label class="form-check-label">
                <input class="form-check-input number status" type="checkbox" name="" value="" id="termsChk">I agree with
                <span class="form-check-sign"></span>
                </label> <a style="color: #f96332;">"Terms and Condition"</a>   
           <input type="hidden" id="termsValue" name="termsValue" value="">
     </div>


            <!-----Terms and Condition Modal----->

            <div class="modal fade" id="termsModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
     <div class="modal-dialog">
        <div class="modal-content">
            <div class="modal-header">
    <h4 class="modal-title" id="myModalLabel">Terms and Conditions</h4>
      </div>
        <div class="modal-body modelheight1" id="modalBody1">
              <p style="text-align:justify;" id="modalTerms">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum non ipsum at magna finibus rhoncus a vitae leo. Phasellus id nibh luctus, gravida elit pellentesque, consectetur sem. Nulla fringilla, nulla et egestas rhoncus, sem risus iaculis neque, eget aliquam mauris erat vitae nulla.
    </p>
         </div>
          <div class="modal-footer">
           <button class="btn btn-primary" data-dismiss="modal" disabled aria-hidden="true" id="agreeBtn">Agree</button>
        </div>
    </div>
 </div>