Again, my thanks for all who have responded on the list, and directly. 

This morning, I disconnected the 8 pin DIN cable from the rear of the unit, verified all the connections, and reinstalled the cable into the rear of the STS2 unit. 

As instructed, I attempted to program it by connecting it directly to the Yaesu G-5400B using the 8 pin DIN cable, but did NOT connect the USB cable. 

When the G-5400B is powered on, the STS2 screen lights up, but displays no text at all. 

I removed power from the G-5400B and held down one of the buttons on the front panel of the STS2, applied power and continued to hold the button down hoping to put the unit into it’s “Menu” mode for programming. No joy. Screen continues to display a light but no text. 

Any ideas on how to troubleshoot further? I have ordered an additional DIN cable but the one I have ohms out correctly on my VOM, and I’ve triple-checked all the connections.