Bypass "Billing" section when customer is paying with gift card - woocommerce - php

Question

My wp theme was custom built and has a great ajax checkout experience, but I am having an issue when customers attempt to pay with a yith gift card that covers the total amount of the cart. Essentially throughout the checkout process there is a single button to proceed through the checkout steps; Shipping>billing>summary.
When a gift card is applied that covers the total amount, customers put in their shipping info, then click next to go to billing, at this point the credit card fields are hidden (as they should be), but the button (which now states "Proceed To Summary") is no longer clickable. The customer cant move from the empty billing page to complete their order. As such, is there a way to bypass the "billing" step if the order total is 0 and go straight to summary so the customer can complete their order?
Here is the code from my theme form-checkout.php :
<?php
/**
* Checkout Form
*
* This template can be overridden by copying it to yourtheme/woocommerce/checkout/form-checkout.php.
*
* HOWEVER, on occasion WooCommerce will need to update template files and you
* (the theme developer) will need to copy the new files to your theme to
* maintain compatibility. We try to do this as little as possible, but it does
* happen. When this occurs the version of the template file will be bumped and
* the readme will list any important changes.
*
* #see https://docs.woocommerce.com/document/template-structure/
* #package WooCommerce/Templates
* #version 3.5.0
*/
if ( ! defined( 'ABSPATH' ) ) {
exit;
}
do_action( 'woocommerce_before_checkout_form', $checkout );
// If checkout registration is disabled and not logged in, the user cannot checkout.
if ( ! $checkout->is_registration_enabled() && $checkout->is_registration_required() && ! is_user_logged_in() ) {
echo esc_html( apply_filters( 'woocommerce_checkout_must_be_logged_in_message', __( 'You must be logged in to checkout.', 'woocommerce' ) ) );
return;
}
?>
<div class="checkout-container d-lg-flex">
<!-- Checkout main -->
<div class="checkout-main">
<!-- Header -->
<div class="checkout-header"><?php _e('Secure checkout', 'woocommerce'); ?></div>
<?php if( !is_user_logged_in() ){ ?>
<div class="checkout-section section-checkout-logreg">
<?php
if( isset($_GET['action']) && $_GET['action'] == 'register' ) {
//wc_get_template( '/checkout/checkout_registration_page.php' );
wc_get_template( 'myaccount/form-registration.php' );
}
else if( isset($_GET['action']) && $_GET['action'] == 'forgot_pass' ) {
//wc_get_template( '/checkout/checkout_registration_page.php' );
wc_get_template( 'myaccount/form-lost-password.php' );
}
else{
//wc_get_template( '/checkout/checkout_login_page.php' );
wc_get_template( 'myaccount/form-login-single.php' );
}
?>
<!-- Button area -->
<div class="checkout-button-area d-flex flex-wrap justify-content-between">
<?php _e('Back To store', 'woocommerce'); ?>
</div>
</div>
<?php } ?>
<!-- Progress -->
<div class="checkout-progress"<?php if(!is_user_logged_in()){ echo ' style="display: none;"'; } ?>>
<div class="progress-step active" id="progress-shipping">
<?php _e('Shipping', 'woocommerce'); ?>
</div>
<div class="progress-step" id="progress-payment">
<?php _e('Payment', 'woocommerce'); ?>
</div>
<div class="progress-step" id="progress-summary">
<?php _e('Summary', 'woocommerce'); ?>
</div>
</div>
<form name="checkout" method="post" class="checkout woocommerce-checkout" action="<?php echo esc_url( wc_get_checkout_url() ); ?>" enctype="multipart/form-data"<?php if(!is_user_logged_in()){ echo ' style="display: none;"'; } ?>>
<?php if ( $checkout->get_checkout_fields() ) : ?>
<?php do_action( 'woocommerce_checkout_before_customer_details' ); ?>
<div id="customer_details">
<!-- Checkout Shipping -->
<div class="checkout-section section-shipping">
<?php do_action( 'woocommerce_checkout_shipping' ); ?>
</div>
<!-- Checkout Billing -->
<div class="checkout-section section-billing" style="display: none;">
<?php do_action( 'woocommerce_checkout_billing' ); ?>
</div>
<!-- Checkout Summary -->
<div class="checkout-section section-summary" style="display: none;">
<div class="row">
<div class="summary-section summary-shipping col-12 col-sm-6">
<div class="summary-section-wrap">
<h4 class="summary-title"><?php _e('Shipping Address', 'woocommerce'); ?></h4>
<button type="button" class="summary-edit" title="<?php _e('Edit', 'woocommerce'); ?>"><?php _e('Edit', 'woocommerce'); ?></button>
<div class="summary-section-content"></div>
</div>
</div>
<div class="summary-section summary-option col-12 col-sm-6">
<div class="summary-section-wrap">
<h4 class="summary-title"><?php _e('Shipping Option', 'woocommerce'); ?></h4>
<button type="button" class="summary-edit" title="<?php _e('Edit', 'woocommerce'); ?>"><?php _e('Edit', 'woocommerce'); ?></button>
<div class="summary-section-content"></div>
</div>
</div>
<div class="summary-section summary-payment col-12 col-sm-6" data-ending="<?php _e('Ending in', 'woocommerce'); ?>">
<div class="summary-section-wrap">
<h4 class="summary-title"><?php _e('Payment Details', 'woocommerce'); ?></h4>
<button type="button" class="summary-edit" title="<?php _e('Edit', 'woocommerce'); ?>"><?php _e('Edit', 'woocommerce'); ?></button>
<div class="summary-section-content"></div>
</div>
</div>
</div>