Onepage Checkout not working CE 1.9

[ProudWorks]

On the onepage checkout page, I am able to go through everything: Billing Information --> Payment Information. Once I get to the Order Review and click on Submit, the page tries to submit the order (a good 5 second or more lag) then it takes me back to the checkout page. No sale is recorded.

Right now I am using the Braintree extension and Pay with Amazon extension. Still on RWD theme. This is a clean install with no modification except for the extensions.

Thanks for helping!

[ACheckout]

Dear @ProudWorks,

Could you please let me know what your domain is? So I can check the issue on your site.

[Mukesh Tiwari]

Hi @ProudWorks

Can you see any console errors in browser?  Check system log and exception log at var/log location.

If there are errors related to checkout then add those to your question.

Thanks

[ProudWorks]

@Mukesh Tiwari

There is no errors in the browser. The var/log folder is empty.

[ProudWorks]

@ACheckout,

The domain name is otcshoppeexpress.com

Since the time I posted this, I have added a new theme. The result is still the same. When checking out, on (https://www.otcshoppeexpress.com/checkout/onepage/) I can complete all the steps up until it submits the order. Once it tries to place the order, it lags for at least 5 seconds (sometimes a bit more), and then it takes me back to https://www.otcshoppeexpress.com/checkout/cart/

Also I wanted to clarify that this is CE 1.9.2.2

Thanks for your help.

[ACheckout]

Hi @ProudWorks,

I see that when use Amazon payment method on your site we will meet the problem: 504 gateway timeout. I think you should increased the ELB timeout for requested ELB's.