Your guy can't reimage your box. It doesn't work that way.
You should do a hard reset and if that doesn't work do some troubleshooting bad cable ,power supply etc
Guide here
its video player and you click on live tv after menu settings configand you have the option to change it
Have you tested your service on another device?
Even though the issue is the same the reasons might be different Discussion of one receiver model should stay in that receiver forum
It's too difficult to help multiple people in one thread which is why hijacking is frowned upon