End stops not registering

Hi,
I am assembling an 840D with the performance kit. I have been able to get the board wired up and connected with everything however I cannot get any of the end stops to register.

None of the 4 switches register in software however they all physically work when connected to a multimeter. Weirdly, it seems that all of the sockets that the end stops go into are already connected, as when I use a multimeter on the two sockets it registers that a current can flow. I dont know if this is normal?

If not I suspect it is a configuration issue but I cannot work out what needs changing. A lot of the configuration pins were incorrect with direction and step pins needing switching for each axis, but as far as I can tell, the end stops all use pin 12 (maybe why they are all connected?) and this is what has been set.

Has anyone got any advice?

Many thanks