The remote for my new Roku Express 4K + wouldn’t pair. I remembered a trick for programming garage door openers and it worked.
I had two remotes from two different Roku Express 4k + devices and neither turned on the Roku or the tv. The green pairing light under the battery cover on one lit up but the other didn’t. I pointed them toward each other about two inches apart and held both pairing buttons at the same time. At first the green light on both remotes flashed slowly, then quickly, then stopped. Suddenly both remotes could turn the tv off and on.
But the volume control and mute button on neither remote functioned. So I pressed home on the first remote, arrowed down to ‘settings’ on the tv screen, then arrowed over to ‘remote and devices.' Next I arrowed over to ‘remotes’ and finally to ‘set up remote for tv control.’ After I followed the steps on the screen, that remote was fully functional. But, I discovered that only one remote connected to the Roku Express 4k+ can control the volume and mute buttons.
I'd like to know more about the issue you are experiencing to assist you best. For clarification, the new remote won't pair with your Roku device. Is that correct? Have you tried following the steps on this support page to see if it helps?