The output you are getting from the notochord means that it couldn't find a Hub. Since the Hub might not be receiving any power it is expected.
Did you wired the RPi and Hub as in this scheme?
Alternatively you can try to connect the [ENABLE] line to the pin 17 (3v3) on the RPi instead of using pin 7 (GPIO 4).
If it is still not working the Led might have been soldered backwards.
Is the anode (+) leg of the led on square pad of the D1 footprint? (EDIT) I made a mistake here, see this postto get the correct polarity of the LED
Another problem might be the power bank. Since they are conceived to recharge batteries, some of them might interrupt the power supply when the withdrew current is negligible (and that would be the case for the Hub, with just a led and the Mux in idle state). Could you try using a 5V wall-wart with an USB output instead?
(the ones used to charge smartphones should work)
If none of the above applies I would need some measurements to try to identify the problem.
Please connect the wall-wart to the Hub, unplug RPi and KCs, and use a tester to measure the voltage at
- pin #1 of jumper JP1
- TP10 (test point near the micro USB connector)
The testpoint TP7 can be used as a reference to Ground.
Let me know how it goes..