Issues with Cisco explorer 8642HDC

Hello - I recently moved into a new home and had the Cox Professional Installation performed. When I moved on Saturday and hooked up the television, we did notice some stuttering, but I didn't pay much attention to it. On Sunday, after working for a bit, neither the remote buttons nor buttons on the cable box would work. Eventually the entire box rebooted itself, and was stuck on a cnF9 code for quite some time. After that, it seemed to work for a bit. Yesterday, same issue. The box stopped working, I manually restarted it, and it worked fine for 30 minutes before crashing again. Today, I couldn't get anything other than a black screen. I noticed a comment on this forum to unplug the box and try it in a different receptacle, but that didn't solve the issue. After a few minutes of the cnF9 code, I had usage for about 5 minutes before all buttons stopped working. I've changed the input from the HDMI cable to component video, but that was no help either, so I am sure it's not a cabling issue. My second television is not hooked into a cable box or DVR, and seems to be working fine. Any suggestions? Can I schedule a tech visit through this forum?