form.phtml

<div class="mp"></div>
<script src="https://www.mercadopago.com/v2/security.js" view="checkout"></script>
<script src="https://sdk.mercadopago.com/js/v2"></script>
        <div class="cho-container"></div>
        <script>
        const mp = new MercadoPago("<?php echo $this->publicKey; ?>", {
                locale: 'es-MX'
        });

        const checkout = mp.checkout({
            preference: {
                id: '<?=$this->pregerenceId?>'
            },
            //autoOpen: true,
            //render: {
            //        container: '.mp', 
            //        label: 'Pagar MercadoPago',
           // }
        });
</script>
<input type="button" class="app-btns primary mercadopagobtn"  value="Pagar con MercadoPago">


<script>
    function mercadopagoOpenHandler(e){
        
        checkout.open();
        return true;
    }

    $('.mercadopagobtn').on('click', function(e) {
        e.preventDefault();
        $('.mercadopagobtn').hasClass('disabled')
        mercadopagoOpenHandler();
        
    });
</script>