Currently it's not connected to anything. Once the problem occurred, I disconnected things to see if it made a difference; it didn't. Usually it's connected to a PCB board I created that connects like a cape. The PCB connects a Bluetooth HM18, LCD 20x2 and 5 push buttons. The audio output an input is also connected, using a balanced connection for one of them (I don't recall as I type on my coach)
Each day it's connected to my computer via USB when I develop. On the weekend I play down stairs in studio, well just a basement now, but it has a pa, which I connect using an insert cable. There it's powered via a wart and usb cable.
It was connect to my computer when it was working last. I was attempting to implement a new service, which means some new code in a new directory. I had modified a configuration file to point to the new directory, but something wasn't working correctly yet. Then I remember trying to make another small change and it stopped booting.