Unable to login after moving site

I have a 4.1.1 site operating at nonprofitname.org. It’s hosted by GoDaddy.

I need a copy of the site to serve as a sandbox. I want the sandbox in my virtual shared server environment (also managed by GoDaddy, but a completely different server/IP, etc.).

I spoke with GoDaddy and they told me to just FTP all of the site files into the new directory. I set up an A name listing for the new location and called it sandbox.nonprofitname.org.

The site at sandbox.nonprofitname.org loads just fine. All of the content appears to be there, the plugins seem to be working, the custom theme is working, etc.

There are two problems which I should have thought of before moving the site:

1) Each internal link on the sandbox site links the user back to the original site. If I type “sandbox.” in front of any URL, the page on the sandbox site loads properly.

2) I can’t log into the sandbox site to correct the URL. sandbox.nonprofitname.org/wp-login.php loads fine, but when I enter my credentials I get redirected back over to the orignal nonprofitname.org/wp-admin panel.

Obviously these two problems are both related to the site name. And I’m sure I should have changed it before I moved it. But I didn’t, and I’ve already spent the good part of the day ftping the site down from the original server to my local machine and then up to the new server from my local machine.

My questions are:

1) I found this Moving WordPress article after I had already moved the site and see now that I should have changed the URL before moving the site. How can I change the necessary URL information by hand in the sandbox copy now (after the fact)?

2) Is it a mistake to make those changes manually? Would it be extremely time consuming?

3) If I need to start over again is there a simpler way to deal with the URL issue than outlined here? codex.www.ads-software.com/Moving_WordPress#Changing_Your_Domain_Name_and_URLs I really don’t like the idea of mucking around with my live site, as it gets a reasonable amount of traffic. Perhaps there is a recommended plugin?

I’d appreciate any help you can offer. If I haven’t asked the right questions here, please feel free to tell me a better way to be looking at this.

Thanks!