New IDC cables helped, but still no cigar
OK, super weird additional findings – boy this is a lot of fun 
So I got my proper 16 pin IDC cables today, which I hooked up and now my duff column is working. But this seems to have exposed some awesome craziness. Now if I got into arudinonme serial and do the test, I get them all lite up – woot I said. Then I noticed that in my monome test that was in the background I was getting crazy button presses being fired. Not touching anything, but with monome test set to toggle, as I start lighting up leds eventually I hit critical mass and monome test starts fireing button presses and led’s start turning off.
Out of curiosity I also fired up nerdscroll to see if my mirror issues was still occuring and it is.
Which made me look again at the break off board.
It seems I have the LED lights pin set upside down (the top one of the pair the one with the sets of 4 wires connecting to it..
I have mine…
bottom top…
8 – 1
16 – 9
Whereas looking at the diagrams again, I think it’s supposed to be
bottom top
1 – 8
9 – 16
I’m assuming I can’t fix that with turning the cable round since that will make the left and right sides switched as well.
So tomorrow evening I will resolder the break off panel and try again.
As much as it’s still buggy, I do feel closer than I was 2 hours ago. At least now all the lights light up. 
Couldn’t wait. Similar issues, just on the column on the far right.
That’s got me thinking it’s not my board, but back at the shield or breakoff pcb level.
First thing I’m thinking is my breakoff pcb header pins. Swap them out tomorrow.
OK, just in case someone finds this and wants to know what was wrong. I will post a run through post at some point of all my gotchas.
The main issue I had was that I was following an old image for my sparkfun board to breakoff wiring. See…
http://post.monome.org/comments.php?DiscussionID=2529&page=1
That has links to the correct one from Jordan – thanks for the new one Jordan.
Once I’d reversed the way my sparkfun to breakoff was soldered it fixed most of my issues.
But I still had some issues.
After going through a million combinations of IDC cable hookups between the breakoff and the shield, I found the correct cable connections and the correct rotation of the cable. That fixed 99% of the issues.
The remaining issues I had was a missing row of lights and 2 missing columns of button presses.
The row was a single frayed wire short on the breakoff pcb from one of my sets of 4 wires. It was just touching the next solder point and that stopped the row from lighting.
The columns were due to the fact that one of my header pins wasn’t soldered. I found this one by identifying the LED ground and where it attached to the breakoff, desoldering it and then voltage checking the wire against all the associated solder points in the breakoff. That showed me that it wasn’t even getting voltage off the pin solder point, all I needed to do was apply the iron to that solder for a second and it all started working again.