Cloned site still redirecting back to live site

A site I was asked to look at is running terribly slow. So I cPanel file back up and a SQL backup and put it on another site to have a play with.

I was firstly able to get to the testing site, but once I had logged into the admin site, it now only every takes me to live site, not the testing site. You cannot believe how frustrating it is.

The only plug in that I can see that may cause this issue is JetPack but I am not sure what to do with it as I don’t want to break the user’s current site.

Any thoughts on how I can access the clone without being constantly redirected?