Checkout Button on Cart Page is not working

[KOBYWong]

the checkout Button on my cart page is not working. It is just refreshing the page. I tested it with two Computers (with Chrome and Firefox on each) and chage other Themes. Each times I tested it as well in incognito mode. Same on my iPhone with Safari. 

Can you please provide me a solution for this?

[KOBYWong]

https://nothing-happened.com/cart

[KOBYWong]

How to fix it?

Thank you 

[KOBYWong]

No add