The crash on AppleTalk startup makes me think there is something weird going on with this particular board, FWIW. The test firmware is not comprehensive, it was written quickly to help diagnose soldering issues where pins were bridged or a whole chip was borked. More subtle issues may be missed by it.
Based on your note about the HDD formatting, I'm assuming the emulated hard drive is working fine. That should rule out most SCSI bus issues and SCSI driver chip problems. Please mention if that's not the case. If the HDD is also not working, those two items probably need checking.
Another option is compiling the normal firmware with debugging support and hang a listener off the UART test pin, and monitor what the board is sending. This is dumb printf() type stuff, and might also not report anything all that useful, but it might give a hint as to where things are crashing.