My roku is plugged directly into a wall outlet. I am getting a repeat message that my tv USB port will not power roku—but my roku is plugged into a wall outlet using the usb I got with my roku. The message appears a few minutes after I turn roku on. Has worked ok for months. I have tried different outlets. Appears to be a problem Only with the Roku unit, as other electronics plugged in these same outlets work fine. I can send model and serial number; but it looks like the unit is malfunctioning and needs to be replaced.
What model Roku (Settings > System > About)?
If it's one that is powered via a USB cable, have you tried using a different wall adapter you may have around, like from a cell phone? Use one with a rated output of at least 1 amp.