Been awhile, but a quick update:
The issue was resolved by getting a new startup panel. It cost me $200 to get one from WinWing, and over three weeks of back and forth... as well as fighting with them over warranty. Once I got the new panel, I connected it and it worked flawlessly. So, the issue was obviously hardware or firmware related.
In the end, it cost me several hours/days of time and effort as well as the monetary loss; I'm not sure if I saved anything, or just paid full price for the startup panel. The warranty clearly means very little, and I hope to never deal with WinWing again. But, I am relieved to be "flying" again. Still working on the MIP which is a different issue altogether, but that's another story.