Following up on the issues some people have encountered with systems that are supposedly non-operational after being assembled, I asked Crowd Supply to send me one of the production boxes so I can investigate the issue. The box arrived yesterday, and I opened it and assembled the system today while shooting a video. I had not made any pre-preparation and the video actually shows me opening the box for the first time.
I hope the video will be a useful pointer - total assembly time 23:03 (no rush), and it shows what needs to be done and how. [ After assembling the system, I stopped the recording and switched it on. As expected, the ST light came on blue, not the screen remained black. That exactly matches the description of the issue others had.
So I flashed the PIC32 with the hex from GitHub (I have a newer hex which I will publish in the coming days, but intentionally flashed it with the current one). I also used the chance to flash the keyboard controller PIC16 with its newer firmware, although that was not necessary. The file is again available from GitHub.
After flashing, the machine started immediately, absolutely no other intervention from my side was needed.
So I can summarize two points for attention:
Flash the newest available firmware into the PIC32 (and optionally into the PIC16 as well) before assembling the system. Note that the PIC32 can only be flashed when the system is on (i.e., displays a solid blue ST light).
There seem to be some issues with defective LCD panels out in some of the boxes. The one in the system today was fine, but one of my early prototypes came with a faulty LCD. This is the only potential source of faults of which I am aware so far. If you come across a panel which is not displaying a nice and clear picture, please contact me or Crowd Supply for a replacement of the panel only.
I also shot a very short few-second video showing the exactly same system after being flashed and assembled.