1. Reset the tv fully. No model number so check the manual and try all the resets there.
2. Check for latest firmware. If you are unsure of which file or procedure call Samsung to walk you through this.
3. After all this, re-pair the remote and be sure the old remote has it's batteries removed.
My smart remote broke so I bought a new one, the new one registers what I am saying, but doesn't do anything. e.g. if I try and search something, it just writes what I say but does nothing, but if I say pause then it works