Question: I inserted a Google Tag Manager code snippet below the body tag but my website will only display a blank white page. When I remove it, the page displays correctly.

```
<!-- Google Tag Manager -->
<noscript>
<iframe src="//www.googletagmanager.com/ns.html?id=GTM-XXXXXX" height="0" width="0" style="display:none;visibility:hidden">
</iframe>
</ noscript> 
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0], j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src= '//www.googletagmanager.com/gtm.js?id='+i +dl;f.parentNode.insertBefore(j,f); })(window,document,'script','dataLayer','GTM-XXXXXX');
</script> 
<!-- End Google Tag Manager -->

```

Answer: 
Just spend half a day on it. If you have the same problem has me it is because you are using Smarty and he doesn't recognise it as Js or something like that.
I had to use `{literal} ... {/literal}` tags. 
Hope this could help someone.
Without many details, it is a little hard to figure this out. 

* Is the main code in the head tag?

`<!-- Google Tag Manager -->
<scrIpt>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-XXXXXX');</script>
<!-- End Google Tag Manager -->`

This script should be as high in the head tag as possible. 

If this script is present and there is nothing else wrong. Then there would be code around this that is breaking, or code inside of it. Are there tags in GTM setup to do something that may cause the page to break? Is it only this page? Can you create a new page, fresh HTML, nothing else on it except a paragraph and headline, add the GTM code? Once you do this, and assuming the H1 and p are visible, then add the rest of your page, piece by piece, until the page breaks. You will then know what is breaking GTM. 

That is the best advice I can offer without taking a look myself. 

-Cheers