Как изменять картинку по клику на миниатюру в форме ZeroBlock в Tilda

<script>
document.addEventListener("DOMContentLoaded", function() {

const productImg = '.product_img';
const formClass = '.form__main';
const optionSize = 'input[name="productimage"]';

function changePic(em){ 
    const imgElem = document.querySelector('.product_img .tn-atom');
    imgElem.style.backgroundImage = 'url('+em+')';
    imgElem.setAttribute("data-original", em);
    imgElem.setAttribute("data-img-zoom-url", em);
};

let formInput = document.querySelectorAll(formClass+' input');
formInput.forEach(function (el, index) {
    el.addEventListener('change',function(e) {
        let form = document.querySelector(formClass);
        
        let imgBgimg = form.querySelector(optionSize+':checked').nextElementSibling;

        let img = imgBgimg.getAttribute("data-original");
        
        changePic(img);
        
        let btnForm = form.querySelector('button');
        let btnUrl = btnForm.getAttribute('href');
        
        if(btnUrl){
            setTimeout(function(){
                btnForm.setAttribute('href', btnUrl.split(':::image=')[0]+':::image='+img);
            }, 100)
        };

    });    
});

});  
</script>