I tried that and it simply won't turn on without all 4 boards plugged in. I also tried moving the remaining three connectors to different places and no luck, still won't turn on. I have the latest firmware too if that makes any difference.

eta: I tried something potentially risky and swapped the controller with another C1 that has 4 good boards. Seems to have fixed it. It works now with any combination of boards connected with the other controller. Kinda strange but I'm not complaining. Thanks for the input VirosaGITS. I appreciate it.