Please be aware that the Roku 3 (4200) 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: Roku Accessories
Could you tell us more about the issue you're experiencing? Please also reply here with the serial number of the Roku device associated with the affected remote. This can be found at the back or underneath the player itself.