Getting Philips Hue to Pair - Mystery Revealed?

openHAB 3.4.0 Build #3029
Using the Ember EM35x Coordinator on a Dual USB Nortek stick

I’m trying to understand how the Philips Hue pairing process works. I have been using mine successfully since I first used OH but I haven’t seen a description how to make it work. Mine stopped working after a reboot and so I went through various steps and it started working, but I have no idea why. So here are some questions:

Let’s say I delete the Username in the Thing Config … How do I restore it?
I’ve used this trick before that I found on a thread here I think:

1. To get username using the Top Hue Button:
  1. http://<BRIDGE_IP_ADDRESS>/debug/clip.html
  2. fill URL with /api
  3. fill MessageBody with something like {"devicetype": "openhabHueBinding#openhab"}
  4. press hue box button
  5. click POST
  6. find username in response.

After that you add the Username to the config … and then what? I disabled the Thing, then Reenabled it. nothing happened …

The thing that made it come Active again was to do a Hue Scan. And it immediately came active. But not sure if that is all that is needed in a normal case.

So what are the definitive steps to get a Hue Bridge running?