FOR-A VTW-400 Video Typewriter – non-functional

The following FOR-A character generator does power on, with the green front panel light illuminated. There’s a beep upon boot-up, fan works, and power is going to each of 4 circuit boards (of which 2 have red lights), but no video signal emerges.

Upon boot-up, unit is supposed to display one of 5 messages via Video and Line Out on its internal condition, but it seems it doesn’t get that far, as whatever video is inputted into the main unit is stopped somewhere within the boards.

Main unit doesn’t communicate with keyboard, although keyboard is getting power (as evidenced when keys illuminated on boot-up, and when Shift Lock key is depressed. No other lights on keyboard turn on when any other keys are depressed except Shift Lock, or Shift (which turns on Shift Lock light).

There’s a reset button on the rear of the keyboard and on the second-from-the-top circuit board, but they have no effect on snapping main unit back to life and enabling some video display.

I cracked open the unit, blew out dust from the slots where the 4 circuit boards connect with the motherboard, and made sure they were pushed in flush – no change.

Circuit boards don’t show any visible sign of corrosion or bad capacitors, and power supply seems sound.

Seller reported this unit was functional until it was pulled in February. Not sure if some severe jostling during shipping affected the unit’s integrity, but everything is encased in very tough metal.

Suggestions?