Maybe it's not paired, even infared needs to be paired, with a code or something
IR receiver might be blocked, do you have anything in front of your TV? Try using the controller much closer to the TV and try all parts of the bottom of the frame.
My Tivo Stream 4K does that about every week. I have to pair the remote to the unit again. If that doesn't work you might need new batteries.
Have you tried new batteries?