EDIT: short version, too many pins. Just because you can connect it there, doesn't mean you should. F5 was one too many.
So, I've attached the teensy to the Ergodox board, and loaded firmware and tested it in aquakeys, and after looking at my layout, I realized the keys that didn't show up were layer-switching keys. No problem, except for row 3.
I've tried three different .hex files, one of which is cubuniac's year-old dropbox hosted TMK build of the qwerty layout. In none of them do I get a response in aquakeys for matrix position 3:8 through 3:13.
I've tested with a multimeter, and found (am I right?) that the pin labelled F4 handles row three ... and there's no impedance on whichever side you'd expect that. I can also find the columns, with impedance fairly low for, say B2 & B3. But shorting B3 to F4 while having aquakeys up does nothing. I can trigger some keys around it, in row 2 and 4 that way, but not row 3. Ever.
Now, I know I damaged it while attaching it. There's a black flea-sized thing that came off. Completely. Near F5 but my pinout sheet says it's AREF. Anyway I reattached it, I think. But the LED near the reset button only very dimly glows. You can't see it anymore in a normally lit room.
But I can, as I've said, load firmware successfully. And make every RH key that isn't in row 3 work ... haven't gotten the left hand attached so I can't test that, just yet.
suggestions? What should I even test for?