So this is what the ReMix board I sent Scott is doing 
So you know, the ReMix was not the K40 drop in, that was the C3D Mini and now the LaserBoard.
Try to follow the concepts in these instructions:
https://cohesion3d.freshdesk.com/support/solutions/articles/5000726542-k40-upgrade-with-cohesion3d-mini-instructions-
And there is a wiring diagram for the ReMix here:
https://cohesion3d.freshdesk.com/support/solutions/articles/5000718963-cohesion3d-remix-pinouts
You need X motor, Y motor, endstops to X Min and Y Max and L and Gnd to fire the laser.
L goes to P2.5 bed - output, and you’ll need a ground from the Laser PSU to the board ground shared as reference for that signal.
However, you should use a separate 24v PSU.to power the Main Power IN screw terminal on the ReMix.
Finally, use the firmware and config files at the bottom of the install guide, the pins should be the same as the C3D Mini, although you may want to double check me on whether I used the Y Min or Y Max pin on the C3D Mini and config file.
Also, DRV8825 means you will need to double the steps per mm.
That should be it.
We don’t remove the pot/ digital panel. Read the FAQ section of the forum to learn more.