Back-Icon in single.php

At the moment this situation:
Included in the single.php is the code. In addition, I have included a Code Block with this code below the sample post.
The code from the single.php should insert above the article a Reply icon, what does not work. The block of code in the sample post works. But now the title of the post has disappeared. Even if I remove the code block again, the title will no longer appear. What is this effect???

This is a good hint. But where must’ll insert this code for the back button?

?><div>
<a href='javascript:history.go(-1)' onMouseOver='self.status=document.referrer;return true' class='icon-reply'  title='zurück'>
<span class='avia_button_ico' data-av_iconfont='entypo-fontello' data-av_icon='ue830' aria-hidden='true'></span>
</a>
</div>
<?php

I have tried several places, nothing works.
This is the Code of template-builder.php:

<?php
	if ( !defined('ABSPATH') ){ die(); }
	
	global $avia_config, $post;

	if ( post_password_required() )
    {
		get_template_part( 'page' ); exit();
    }

	/*
	 * get_header is a basic wordpress function, used to retrieve the header.php file in your theme directory.
	 */
	 get_header();
	 

 	 // set up post data
	 setup_postdata( $post );

	 //check if we want to display breadcumb and title
	 if( get_post_meta(get_the_ID(), 'header', true) != 'no') echo avia_title();
	 
	 do_action( 'ava_after_main_title' );

	 //filter the content for content builder elements
	 $content = apply_filters('avia_builder_precompile', get_post_meta(get_the_ID(), '_aviaLayoutBuilderCleanData', true));

	 //if user views a preview me must use the content because WordPress doesn't update the post meta field
	if(is_preview())
	{
		$content = apply_filters('avia_builder_precompile', get_the_content());
	}

	 //check first builder element. if its a section or a fullwidth slider we dont need to create the default openeing divs here

	 $first_el = isset(ShortcodeHelper::$tree[0]) ? ShortcodeHelper::$tree[0] : false;
	 $last_el  = !empty(ShortcodeHelper::$tree)   ? end(ShortcodeHelper::$tree) : false;
	 if(!$first_el || !in_array($first_el['tag'], AviaBuilder::$full_el ) )
	 {
        echo avia_new_section(array('close'=>false,'main_container'=>true, 'class'=>'main_color container_wrap_first'));
	 }
	
	$content = apply_filters('the_content', $content);
	$content = apply_filters('avf_template_builder_content', $content);
	echo $content;

	$avia_wp_link_pages_args = apply_filters('avf_wp_link_pages_args', array(
																			'before' =>'<nav class="pagination_split_post">'.__('Pages:','avia_framework'),
														                    'after'  =>'</nav>',
														                    'pagelink' => '<span>%</span>',
														                    'separator'        => ' ',
														                    ));

	wp_link_pages($avia_wp_link_pages_args);

	
	
	//only close divs if the user didnt add fullwidth slider elements at the end. also skip sidebar if the last element is a slider
	if(!$last_el || !in_array($last_el['tag'], AviaBuilder::$full_el_no_section ) )
	{
		$cm = avia_section_close_markup();

		echo "</div>";
		echo "</div>$cm <!-- section close by builder template -->";

		//get the sidebar
		if (is_singular('post')) {
		    $avia_config['currently_viewing'] = 'blog';
		}else{
		    $avia_config['currently_viewing'] = 'page';
		}
		get_sidebar();
	}
	else
	{
		echo "<div><div>";
		
	}

echo avia_sc_section::$close_overlay;
echo '		</div><!--end builder template-->';
echo '</div><!-- close default .container_wrap element -->';

get_footer();

Where should I insert the code block? Below the article I tested this code. He destroyed the post. The title disappears. Please visit the link. In the future, there are several editors. These editors are not to insert a block of code. I want to display the icon automatically over any post over the post title.

I have now inserted the code in the single.php. It works, but it does’nt appear the icon but the numbers “ue830”. What code should I add to make the icon appear? Now, in the code: data-av_icon = ‘ue830’. See the link please – you can see this over the title.

Thank you, Ismael. That was the solution. I’ve already tried this before, but Notepad ++ always made the symbol to a question mark. Now I have tried in the editor explicitly set the encoding of the file to utf8. And now the icon is maintained. I am very happy!