functions.php blank page after updating

Hi,
Hope you can help me! It’s driving me crazy.

I am trying to edit functions.php of a child-theme.

This is what I had on the file:

<?php
/*    All child theme functions go here
----------------------------------------------- */
// Woocommerce New Customer Admin Notification Email
add_action('woocommerce_created_customer', 'admin_email_on_registration');
function admin_email_on_registration() {
    $user_id = get_current_user_id();
    wp_new_user_notification( $user_id );
}

?>

And I wanted to add this :

// Hook in
add_filter( 'woocommerce_checkout_fields' , 'custom_override_checkout_fields' );

// Our hooked in function - $fields is passed via the filter!
function custom_override_checkout_fields( $fields ) {
unset($fields['order']['order_comments']);

return $fields;
}

But when I click the update button, it only returns a blank page.
I already tried editing in a text editor like notepad++ and upload by FTP but I always have the same result, I deleted and created a new functions.php and it’s the same, even changed permissions from 644 to 755 and still the same…

What else can I do? Because anything else I had to the file it’s giving the blank page.

Thank you