Site Stopped Working - Can't Checkout

Recently, our working ZenCart server was powered down due to an outage at the hosting company. It was brought back online and now our site is accessible. However, when going to the checkout area, it hangs and finally times out with the following error:

The page isn't redirecting properly.

Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

*   This problem can sometimes be caused by disabling or refusing to accept
      cookies.

Also, when trying to go directly to the PayPal Express checkout, we get tons of these errors: "- (6) Couldn't resolve host 'api-3t.paypal.com'"

From researching past tickets, I see that this could be caused by DNS issues with the host. My question is, can I do anything to remedy this in cPanel?

NOTE: I should mention that I have installed the Fast and Easy Checkout module which loads the checkout.html on one page. However, this was working prior to the server going down so it isn't a configuration issue. I am leaning towards a DNS problem but I don't know how to check that out. The site is functional in every other way except checking out through zencart or through PayPal Express. We have been down for almost two days now and need some help!

UPDATE: The host got back to me and said the following:

In WHM, Basic Settings, there should be an option for the resolvers you can use. These are DNS servers that your server will use to resolve domains to IPs, which is what is failing. Use these two:

216.234.234.30
207.218.192.38

This should allow your server to resolve properly. The ones that are in your datacenter aren't working as they should.

QUESTION: So I went to my cPanel and went to "Resolver Configuration" under the Networking Setup menu. I entered the above two IP's as the primary and secondary resolvers.

What else would need to be done?

Is there anything else under cPanel that I would have to do with these IP's?

UPDATE: The tech support at the hosting company changed the resolvers, but still our site only hangs when you hit the Checkout button or the orange PayPal Express button. Any ideas?

I even set up a test store and DISABLED all shipping and payment modules (except Check Money order) and it still hangs trying to go to the Checkout area. I need some help here because we're losing a lot of sales.

Any help would be appreciated please.

Hmmmm....even when I select the "Estimate Shipping" button, it hangs trying to communicate.

It would seem that any call to UPS, USPS, or PayPal may be failing in some way and causing the system to hang. Any idea on how to verify this or get around it?

When the estimator does finally come up, it doesn't list any shipping options, as if it couldn't communicate with any of the UPS or USPS API's. See attached screenshot.

Hi there,
I just wanted to mention this in case your issue was caused by the same problem, if it is then you will run into it again. I had the same error as you and it turned out to be a bug in the store credit addon module. The customer who was experiencing the error during checkout had used store credit for their last order. I checked in the store credit module in the admin and it showed their balance as -0.00 which was messing up the checkout. I changed it to 0.00 and it fixed the error :)

Sounds like your Hoster had a Server crash of some kind and they are the ones you should be talking to. They know best what any Hosting account problems are and how to fix them. This is or should be, part of the basic Support offered by your Hoster.