When you first power up your circular gray hub, it should be pulsing blue. If you are not seeing this light, press and hold the large round button on the hub for 15 seconds.
If your hub still isn’t blinking blue, try plugging the power cable into a different outlet. Make sure both the power cable and connector cables are firmly plugged into the hub. Finally, try a reset with instructions here: How do I reset my device?
Please note that your hub will only blink blue during the setup process.