I guess it depends on what the technician said means. In your initial post, I saw you describing a home contractor's attempt at installing a smart panel for video/data services which usually results in a hot mess and is not the service provider's problem so I can completely understand why you would not have been able to figure out what you needed to do to get services working.
Now if the technician that was out for the install identified an issue that was outside of the home and not related to any of this smart panel wiring, you have a good case for requesting a credit for the installation as how I believe it's still Cox policy to refund failed self-install fees if the problem was something on Cox's end. I should probably emphasize the if it was on Cox's end of the issue. Just because you couldn't figure it out and needed a technician to help doesn't mean the issue was Cox's fault. That said, good luck and congratulations on purchasing your new home. Considering the amount of money that changes hands in that process, it may be easier to just consider the cost of establishing services part of the process.