I think first thing i would do is just unplug it for a few mins. Might as well unplug the Xbox HDMI from the RokuTV as well. When you plug it back in, see if reboots normally. Then reconnect Xbox.
Also try some new batteries in the Remote and give it (the remote) a pretty good whack. Would not be the first user to receive bad batteries with a remote.
Install the official Roku remote mobile app to your phone, available from both Apple and Play Stores. Then see if the mobile app is able to connect to your RokuTV and you regain some control over it. (May not work if the RokuTV not connected to a network since both devices (RokuTV and phone) must be on same network.
The final thing to try (although not great idea when you are having trouble connecting to a network and compounded when you do not have a working remote) is to perform a factory reset. (Press and hold the Reset button for 30+ seconds). *Note: you cannot use the mobile app to setup/activate the RokuTV. Must use a physical remote to complete setup before mobile app can be used.
----
Generally, for warranty issues with a RokuTV, you have to contact the manufacturer of the RokuTV. https://community.roku.com/t5/Manufacturer-support-warranty-resources/Contacting-Support-for-Your-Roku-TV/m-p/698232#M9
However, if all the above does not work and TV is less than a week old, if practical, just return to place of purchase and get a new one. If not practical, I would probably head to Walmart/Target/Best Buy etc, and purchase either an inexpensive universal streaming IR remote compatible with RokuTVs and see if that gets me going, or the Roku Voice Remote. (would help narrow down issue to bad remote). I would probably just buy both and return the unwanted one later if helped in diagnosing issue.
You can test your current Roku remote by pointing it at your cell phone (while in camera mode) and pushing the remote buttons. Each button should produce a purple or red light noticeable to the camera that you can see on the phone screen. At least tells you if the buttons on the remote are actually working.
-----
Feel free to update or if you need more help.
