How are you powering the device? Is the Express+ plugged into the TV USB port or is plugged into a wall outlet with the provided cables? We would recommend trying to power the device through the wall outlet with a different set of cables to see if that resolves your issue.
If you are still unable to power your device, please send me a PM with your Roku account email address, and include the serial number of the Roku device from Settings>System>About. I'll be able to assist you further from there.