The TV won't power on.
Roku doesn't manufacture "Roku TV" sets, it only supplies the Roku operating system. This sounds like a hardware issue that needs to be referred to the manufacturer of the set.
Manufacturer support contacts for Roku TVs: https://community.roku.com/t5/Manufacturer-Support-Warranty-Resources/Contacting-Support-for-Your-Ro...
Also it could be IR interference from another remote in the room, check the cushions or under a book? Pull the batteries out of all remotes in the room.