add_action( 'woocommerce_before_checkout_form', 'add_return_to_cart_notice_button' );
function add_return_to_cart_notice_button(){

    // HERE Type your displayed message and text button
    $message = __('Go back to the Cart page', 'woocommerce');
    $button_text = __('Back to Cart', 'woocommerce');

    $cart_link = WC()->cart->get_cart_url();

    wc_add_notice( '<a href="' . $cart_link . '" class="button wc-forward">' . $button_text . '</a>' . $message, 'notice' );
}