Bands are shipped in factory mode and need to be woken up when ready for use.
How to do so
Firmly bend the strap away from the plastic pod
It's pretty durable, so don't worry about being too delicate.
Fully insert the pod into any USB port (i.e. on a computer or phone charger) for a few seconds to wake
The pod can be plugged in screenside up or down. Depending on the USB port you're using, you may need to try both ways.
Confirm it's awake
If the screen goes on for a few seconds when you swipe up or down from middle of pod face, the device is on.
If the screen doesn't turn on
ensure it's inserted squarely, and all the way into the USB port
try plugging it in the other way around, as it's possible it may have been inserted wrong side up for your USB connector