If it's less than a year old, yes it should be under warranty. Send a private message to @RokuDanny-R or @RokuTannerD with your account information and they can assist you.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
I just got the Roku Streaming Stick+, had a little issue with the remote. I think that is resolved? HOWEVER, while I was trouble shooting that I noticed that the streaming stick was hot and well as the adapter. When I turned off the tv I left it to cool for awhile BUT when I checked it was still hot, not warm, hot. So I disconnected it.
To start: I have it hooked up to the tv’s HDMI and the USB adapter provided. When I noticed it was “HOT” I disconnected the HDMI “only” but kept the USB connected. Now with the TV OFF, the connection of the USB adapter is “WARM” not “HOT”.