For 3 days, I kept receiving a message that the USB wasn’t receiving sufficient power and now I can’t power my device on.
Are you using the supplied USB power adapter and not your TV's USB port? Do you have another USB adapter/charger for a phone or tablet that you can try?
Thanks for your inquiry.
We would recommend taking a look at the troubleshooting steps provided by our Support page here: What should I do if the red light is flashing or I ... - Roku
Does this clear up the issue you are seeing? Please keep us posted.