just-boris/index.html

## index.html
<!DOCTYPE html>
<html>
<head>
    <title>Не открывается балун</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script src="//api-maps.yandex.ru/2.0/?load=package.standard,package.clusters&lang=ru-RU" type="text/javascript"></script>

<script type="text/javascript">
var markers = [], clusterer;
ymaps.ready(init);
function init () {
    var myMap = new ymaps.Map("map", {
            center: [54.83, 37.11],
       behaviors: ['default', 'scrollZoom'],
            zoom: 5
        });
    myMap.controls.add('zoomControl', { left: 5, top: 10 });
    function generateMarkers(tlCorner, brCorner, count) {
        var deltaLat = tlCorner[0] - brCorner[0],
            deltaLon = brCorner[1] - tlCorner[1],
            markers = [];
        for(var i = 0; i < count; i++) {
            var lat = brCorner[0] + Math.random()*deltaLat,
                lon = tlCorner[1] + Math.random()*deltaLon;
            markers.push([lat, lon]);
        }
        return markers;
    }
    clusterer = new ymaps.Clusterer({clusterDisableClickZoom: true});
    //markers= new ymaps.GeoObjectCollection();
    [[54.51,35.90],[55.77,37.49],[55.00,37.76],[53.87,37.08],[55.11,37.18],[57.10,39.83],[56.88,37.11],[53.87,38.81],[56.63,39.02],[54.75,36.36]].forEach(function(coords, index) {
        var myPlacemark = new ymaps.Placemark(coords, {index: index+1, balloonContent: coords.toString(), balloonContentHeader: 'Метка ' + (index+1)});
        clusterer.add(myPlacemark);
        markers.push(myPlacemark);
    });
    myMap.geoObjects.add(clusterer);
}
//открыть балун с меткой по индексу
function openBalloon(index) {
    var iterator = clusterer.getIterator(),
        checkAndOpen = function(object) {
            if(object.properties.get('index') === index) {
                marker.state.set('activeObject', object);
                marker.balloon.open();
            }
        },
        marker;
    while(marker = iterator.getNext()) {
      if(marker instanceof ymaps.Placemark) {
        	checkAndOpen(marker);
        }
        else {
            marker.properties.getAll().geoObjects.forEach(checkAndOpen);
        }
    }
}
</script>
</head>
<body>
    <div id="map" style="width:400px; height:300px"></div>
    <button onclick="openBalloon(8);">Открыть балун c меткой №8</button>
</body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>Не открывается балун</title>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<script src="//api-maps.yandex.ru/2.0/?load=package.standard,package.clusters&lang=ru-RU" type="text/javascript"></script>

	<script type="text/javascript">
	var markers = [], clusterer;
	ymaps.ready(init);
	function init () {
	var myMap = new ymaps.Map("map", {
	center: [54.83, 37.11],
	behaviors: ['default', 'scrollZoom'],
	zoom: 5
	});
	myMap.controls.add('zoomControl', { left: 5, top: 10 });
	function generateMarkers(tlCorner, brCorner, count) {
	var deltaLat = tlCorner[0] - brCorner[0],
	deltaLon = brCorner[1] - tlCorner[1],
	markers = [];
	for(var i = 0; i < count; i++) {
	var lat = brCorner[0] + Math.random()*deltaLat,
	lon = tlCorner[1] + Math.random()*deltaLon;
	markers.push([lat, lon]);
	}
	return markers;
	}
	clusterer = new ymaps.Clusterer({clusterDisableClickZoom: true});
	//markers= new ymaps.GeoObjectCollection();
	[[54.51,35.90],[55.77,37.49],[55.00,37.76],[53.87,37.08],[55.11,37.18],[57.10,39.83],[56.88,37.11],[53.87,38.81],[56.63,39.02],[54.75,36.36]].forEach(function(coords, index) {
	var myPlacemark = new ymaps.Placemark(coords, {index: index+1, balloonContent: coords.toString(), balloonContentHeader: 'Метка ' + (index+1)});
	clusterer.add(myPlacemark);
	markers.push(myPlacemark);
	});
	myMap.geoObjects.add(clusterer);
	}
	//открыть балун с меткой по индексу
	function openBalloon(index) {
	var iterator = clusterer.getIterator(),
	checkAndOpen = function(object) {
	if(object.properties.get('index') === index) {
	marker.state.set('activeObject', object);
	marker.balloon.open();
	}
	},
	marker;
	while(marker = iterator.getNext()) {
	if(marker instanceof ymaps.Placemark) {
	checkAndOpen(marker);
	}
	else {
	marker.properties.getAll().geoObjects.forEach(checkAndOpen);
	}
	}
	}
	</script>
	</head>
	<body>
	<div id="map" style="width:400px; height:300px"></div>
	<button onclick="openBalloon(8);">Открыть балун c меткой №8</button>
	</body>
	</html>