Thanks for reaching out regarding the issue you are experiencing.
Please be aware that the Roku 3 is an older Roku device that is no longer under warranty. It's possible that the remote may simply be on its way out. If you need a replacement remote for your Roku device, you can purchase a compatible remote on our Products page here: https://www.roku.com/products/accessories/player
No, it's not the remote control being "out of warranty." These remotes are durable, but they eat batteries like nothing else I own. I go through approx. 12 batteries per year on our main room remote, and it's always been that way. The remote isn't "on it's way out."
Please send me a PM (private message) with your Roku account email address, and include the serial number of the Roku device from Settings>System>About along with a summary of the issue you are experiencing. I'll be able to assist you further from there.