Change Price Of All Product to $0 On Click Add To Cart Button

Or can I set a hidden field on button 2 and change the price to 0 using that?

<input type=”hidden” name=”custom_price” value=”0″ />

I found this link that creates a plugin the overrides the price of all products added to the cart.

https://webkul.com/blog/woocommerce-set-custom-product-price-when-adding-to-cart/

How can I apply this to only when the second add to cart button is used?

Solved!

/**
 * Change Price to $0. Added variation-add-to-cart-button2.php. to woocommerce/includes/wc-template-functions.php and added .btnfree to button class
 */

add_action( 'wp_footer', 'hiddenproductfield' );
function hiddenproductfield() {
    global $product;

    
    ?>
        <script type="text/javascript">
            (function($){
                $('button.btnfree').click( function(){

                    $('<input>').attr({type: 'hidden', name: 'quotesystem', value: 'quotesystem'}).appendTo('form');

                });
            })(jQuery);
        </script>
    <?php
}

function add_cart_item_data( $cart_item_data, $product_id, $variation_id ) {
	// Has our option been selected?
	if( ! empty( $_POST['quotesystem'] ) ) {
		$product = wc_get_product( $product_id );
		$price = $product->get_price();
		// Store the overall price for the product, including the cost of the warranty
		$cart_item_data['quote_price'] = $price * 0;
	}
	return $cart_item_data;
}
add_filter( 'woocommerce_add_cart_item_data', 'add_cart_item_data', 10, 3 );

function before_calculate_totals( $cart_obj ) {
  if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
    return;
  }
  // Iterate through each cart item
  foreach( $cart_obj->get_cart() as $key=>$value ) {
    if( isset( $value['quote_price'] ) ) {
      $price = $value['quote_price'];
      $value['data']->set_price( ( $price ) );
    }
  }
}
add_action( 'woocommerce_before_calculate_totals', 'before_calculate_totals', 10, 1 );