If you go to the Diagnostics screen in Mach3 activating estop should cause a port 1 pin to alter state and the Emergency indicator to come on. If that is so you are wired up and configured correctly. I have this BoB, but unfortunately I am not able to confirm P4 is the appropriate place to take 5v as it is installed in a control box which is not easily accessible. I believe that the p10 input floats to 5v and only needs a connection to, or disconnection from, GND to activate.

While I think about it, is the 12-24v power connected ?

If you need the BoB manual, you can download it here:- https://www.dropbox.com/s/gfq4isvihn...rd-EN.pdf?dl=0