Here was the thread that confirmed the mystery wiring… looks like it may not be compatible with current min Rambo boards: Installing a new mini Rambo, questions?
Doh… maybe the old limit switch does work, looks like I installed it wrong when I swapped out the board. There is a good picture on the thread here: Z-axis Bed Probing not working
Of how it is suppose to be wired, I had it rotated 90 degrees so on the wrong pins hence probably why it crashed the board…