As to the power message: most TVs still only have USB 2.0 ports, which per spec offer 500 mA of 5V power. Some external hard drives require more power than that, hence the message. If it's an external drive with a spinning platter, the port simply can't provide enough power. If the message is appearing using a "normal" USB thumb drive, and the message doesn't go away if the drive is removed, then it sounds like there's a hardware issue with the TV. For that, you have to contact the TV manufacturer, as Roku doesn't make the TVs themselves.
Final note: this really isn't for recording OTA broadcasts. It's designed solely as a buffer to allow pausing and rewinding what you're watching. I've never connected a drive to my Roku TVs, but I'm not aware of any menu option to manually record a show (either in progress or at a later time), and you certainly can't record something and switch to another channel. No Roku TV has more than a single OTA tuner, so there's no way to watch something and record something else. For that you need another device, such as the Silicon Dust HDHomeRun devices or a PC with an OTA tuner card. I use an HDHomeRun Flex 4K for my OTA recording, controlled by a HTPC running J River Media Center. Since Microsoft dropped their really nice Windows Media Center from Win 10, it was the best replacement I could find.
Dan
Roku Community Streaming Expert
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