jQuery UI filter, Full HTML and hook_block_view_VIEW_NAME_alter
I was able to make it work with the modules installed ( jQuery plugins , jQuery UI filter and jQuery UI filter accordion). The trick was to include the following Javascript in the template yourtheme_preprocess_page() and in the HTML use the div with id="accordion" of the official example ( https://jqueryui.com/accordion/ ).

drupal_add_js(' jQuery(function() {
var icons = {
  header: "ui-icon-circle-arrow-e",
  activeHeader: "ui-icon-circle-arrow-s"
};
jQuery( "#accordion" ).accordion({
  icons: icons
});
jQuery( "#toggle" ).button().click(function() {
  if ( jQuery( "#accordion" ).accordion( "option", "icons" ) ) {
    jQuery( "#accordion" ).accordion( "option", "icons", null );
  } else {
    jQuery( "#accordion" ).accordion( "option", "icons", icons );
  }
});
  });', array('type' =&gt; 'inline'));