Found this and it worked!
"I had the same issue and what ended up working for me was a manual pairing of the remote to the TV. I held the back button and the play/pause button down together for a few seconds to pair. Once that was done, when I hit the 123 button, a number pad popped up to enter the pin. While the rest of the remote had previously worked without the manual pairing, the 123 button did not until after. Hope this helps others."