Remote pairing

Cable TV not working. Went through troubleshooting procedures with tech, who finally suggested I needed a new cable box. Got a new one, with a new power supply and remote. Connected new cable box. Pilot light comes on. Pressed “on” button on new remote to turn TV on. No response. Tried unpairing new cable remote. Appeared to be successful. TV still doesn’t respond to new remote. Tried old remote. It turns on TV and it displays welcoming messages then asks for preferred language TV doesn’t respond to remote , new or old, and then goes to “Do you want to keep using Voice. Guidance “ screen. There it freezes and doesn’t respond to any remote. Why?