Change layer properties from an infowindow link

<!DOCTYPE html>
<html>
  <head>
    <title>Change layer things from infowindow links | CartoDB.js</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
    <meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
    <link rel="shortcut icon" href="https://cartodb.com/assets/favicon.ico" />
    <style>
      html, body, #map { height: 100%; padding: 0; margin: 0; }
    </style>
    <link rel="stylesheet" href="https://libs.cartocdn.com/cartodb.js/v3/themes/css/cartodb.css" />
  </head>
  <body>
    <div id="map"></div>
 
    
    <script src="https://libs.cartocdn.com/cartodb.js/v3/cartodb.uncompressed.js"></script>
 
    <script type="infowindow/html" id="infowindow_template">
      <div class="cartodb-popup">
        <a href="#close" class="cartodb-popup-close-button close">x</a>
 
         <div class="cartodb-popup-content-wrapper">
           <div class="cartodb-popup-content">
             <a href="#/open-something" id="link">Change points color</a>
           </div>
         </div>
         <div class="cartodb-popup-tip-container"></div>
      </div>
    </script>
 
 
    <script>
 
      var layer;
      var colors = ['red', 'blue', 'yellow', 'brown', 'green', 'orange'];
 
      // Custom infowindow
      _.extend(cdb.geo.ui.Infowindow.prototype, {
 
        events: function(){
          return _.extend({},cdb.geo.ui.Infowindow.prototype.events,{
            'click a#link': '_onLinkClick'
          });
        },
 
        _onLinkClick: function(e) {
          console.log(e, this.model, layer);
          var i = Math.floor(Math.random() * 6);
          layer.setCartoCSS('#layer { marker-fill: ' + colors[i] + ' }')
        }
 
      });
 
 
      function main() {
 
        cartodb.createVis('map', 'https://documentation.cartodb.com/api/v2/viz/7eb2096a-51d9-11e3-89a7-5404a6a683d5/viz.json', {
          shareable: false,
          title: false,
          description: false,
          search: false,
          tiles_loader: true,
          center_lat: 42,
          center_lon: -3,
          zoom: 6,
          legends: false
        })
        .done(function(vis, layers) {
          layer = layers[1];
 
          var infowindow = layer.getSubLayer(0).infowindow;
          infowindow.set('template', function() {
            return $('#infowindow_template').html();
          });
        })
        .error(function(err) {
          console.log(err);
        });
      }
 
      window.onload = main;
    </script>
  </body>
</html>

Modified http://libs.cartocdn.com/cartodb.js/v3/cartodb.uncompressed.js to a secure url

https://libs.cartocdn.com/cartodb.js/v3/cartodb.uncompressed.js