I built my first CrowBox a few weeks ago and have been pretty successful in getting a group interested. Currently they visit us most days and have gotten pretty brave about eating out of the box.
When attempting to go to phase 2 progress stopped however. The few times that they did accidentally trigger the door they got scared and immediately left. After a few days they quite coming altogether, and I had to back the phase back to 1.
To combat this, I have made some modifications to CrOS to add an additional stage between 1 and 2. Specifically I've added a random component where they box will open at random approximately once ever 10 minutes (configurable), and stay open for a longer period of time. My hope is that they will get used to just having to wait for it, and then will start to associate the noises with a reward so that it won't scare them.
Not sure if anyone is interested in the code for this, but happy to supply it. I'd also be happy to contribute it back to the github repo, but would need access to create a pull request.
Happy crow befriending!