Remote won’t stop blinking green

You can try this procedure from Tivoburkee :

You can also unplug the roku from its power for a bit, have the remote ready with battery door off and one battery in, now power the roku when the roku name stops bouncing put in the second battery and press and hold the pairing key for 3 to 5 seconds and release. Just let it communicate with roku it is all right if the light goes oyt in the battery compartment don't press anything until you get a big DONE onscreen.

I have exactly the same issue with my remote. It's been working fine until this week, now it won't pair. As soon as new batteries are inserted the green light flashes, but nothing appears on the Roku screen. The pairing screen on the Roku just spins until it says "No remote found".

Hi there, you probably have already found a solution to your remote control challenges but I wanted to share with you and the community what worked for me.  Another user suggested changing the wireless/wifi settings on the Roku from 5G to 2.4G as there could be signal interference between the streaming stick and remote.  I did what they suggested and as I write this, the remote has been working perfectly for a week now.  Prior to me making the change, I'd be lucky to get 24 hours out of my remote, with most of the time only an hour or two.

So in summary, take a look at your Roku wireless settings and if it's set to a 5G network, change it to 2.4G; if it's already set to a 2.4G, try the opposite and change it to 5G!