countdown.js

$(document).ready(function() {
    StartServiceLiveCheck();
});

function StartServiceLiveCheck() {
    UpdateServiceLiveCheck();
    setTimeout("StartServiceLiveCheck()", 5000);
}

function UpdateServiceLiveCheck() {
    $.ajax({
        url: "/isLive",
        success: function(data) {
            if (data.indexOf("true") != -1) {
                $("#notlive").hide();
                $("#live").fadeIn('fast');
                $('.countdown').delay(2000).animate({ backgroundColor: "#7f3e19" }, 'slow');
                $(".mobile-liveservice").show();
            }
        }
    });
    goLive = function() {
      $('#churchonline_counter .live').show();
      $('#churchonline_counter .co-header-countdown-time').hide();
    };
}    
      jQuery(function() {
        days = void 0;
        hours = void 0;
        minutes = void 0;
        seconds = void 0;
        intervalId = void 0;
        return $.ajax({
          url: "/api/data.json",
          dataType: "json",
          success: function(data) {
              
             var seconds_till;
             const now = new Date();
             const eventStartTime = new Date(data.response.item.eventStartTime);
             const eventEndTime = new Date(data.response.item.eventEndTime);
            
            $("#churchonline_counter").show();
              if (data.response.item.isLive) {
                  return goLive();
                  
              } else if (now > eventEndTime) {
                $("#churchonline_counter .live").hide();
                $('#churchonline_counter .co-header-countdown-time').show();
                  return;
                  
              } else {
                  seconds_till = (eventStartTime - now) / 1000;
              
              days = Math.floor(seconds_till / 86400);
              hours = Math.floor((seconds_till % 86400) / 3600);
              minutes = Math.floor((seconds_till % 3600) / 60);
              seconds = Math.floor(seconds_till % 60);
              return intervalId = setInterval(function() {
                if (--seconds < 0) {
                  seconds = 59;
                  if (--minutes < 0) {
                    minutes = 59;
                    if (--hours < 0) {
                      hours = 23;
                      if (--days < 0) {
                        days = 0;
                      }
                    }
                  }
                }

        if (days.toString() == 1) {
          $(".co-countdown-days").html("1");
        } else {
          $(".co-countdown-days").html((hours.toString().length < 2 ? days : days));
        };
        if (hours.toString() == 1) {
          $(".co-countdown-hours").html("1");
        } else {
          $(".co-countdown-hours").html((hours.toString().length < 2 ? hours : hours));
        };
        if (minutes.toString() == 1) {
          $(".co-countdown-mins").html("1");
        } else {
          $(".co-countdown-mins").html((minutes.toString().length < 2 ? minutes : minutes) + " ");
        };
        $(".co-countdown-secs").html((seconds.toString().length < 2 ? "0" + seconds : seconds));
        if (days === 00) {
          $('.daysAll').hide();
        };
        if (hours === 00) {
          $('.hoursAll').hide();
        };
        if (seconds === 0 && minutes === 10 && hours === 0 && days === 0) {
          return clearInterval(intervalId);
        };
        $("#eventTitle").html((data.response.item.title));
              }, 1000);
            }
          },
          error: function(xhr, ajaxOptions, thrownError) {
            return console.log(thrownError);
          }
        });
      });

data.json.twig

{% header "Content-Type: application/json; charset=utf-8" %}
{% header "Access-Control-Allow-Origin: *" %}
{% set currentEventId = craft.app.request.segment(3) %}
{% for event in craft.calendar.events({id: 'not ' ~ currentEventId,rangeStart: 'today',rangeEnd: '1 month',limit: 1}) %}
{
    "meta": {
        "status": 200 },
        "response": {
            "item": {
                "isLive": {% include 'isLive.twig' %},
                "eventStartTime": "{{ event.startDate.format("Y-m-d G:i:s") }}",
                "eventEndTime": "{{ event.endDate.format("Y-m-d G:i:s") }}",
                "title": "{{ event.title }}"
            }
        }
    }
{% endfor %}

please update the interval function as following.

`intervalId = setInterval(function() {

if (days <= 0 && hours <= 0 && minutes <= 0 && seconds <= 0) { clearInterval(intervalId);

$("#churchonline_counter .live").hide();
$("#churchonline_counter .co-header-countdown-time").hide();
$("#churchonline_counter .event-ended").show();

return;

}

if (--seconds < 0) { seconds = 59; if (--minutes < 0) { minutes = 59; if (--hours < 0) { hours = 23; if (--days < 0) { days = 0; } } } }

$(".co-countdown-days").html(days); $(".co-countdown-hours").html(hours); $(".co-countdown-mins").html(minutes); $(".co-countdown-secs").html((seconds.toString().length < 2 ? "0" + seconds : seconds));

if (days === 0) $('.daysAll').hide(); if (hours === 0) $('.hoursAll').hide();

$("#eventTitle").html(data.response.item.title);

}, 1000); `

Did not solve the issue. The problem seems to be on craft calendar side. Only thing this does is show event ended. It didnt allow the countdown to reset to the next event as I was needing.