NCD Explora Pro (was Re: NCD19 / Xncd19)

Similarly, I?m trying to resurrect an NCD Explora Pro, and haven?t found much more than broken links. It?s one of their ?plug a keyboard, mouse, and monitor into the box? X terminals. Plugging in a keyboard, mouse, VGA panel, and Ethernet, I get a steady green light at startup and ?donk donk? noise, then nothing, no sync on the panel. I haven?t tried its serial port yet to see if its boot ROM console was perhaps rerouted there, and I haven?t found documentation on how to do any sort of ?factory reset? of the device. I have a Raspberry Pi 3 with a USB Ethernet dongle that it?s plugged into, but I can?t remember how to use ARP on an isolated network to find the IP address of the other system. If anyone has any pointers, I?d definitely appreciate them. Same for the software to actually operate it as an X terminal. -- Chris