Just got mine up and running after a bit of digging around and FANTASTIC help from Zax @T2Laser Software.
I am only using the X and Y Axis homing switches and I am using both T2Laser Software and LaserGrbl software. When using T2 software you need to upload firmware V1.1f XY Home sw.
The GRBL settings you should look at are $5 (Home Switch type - NO or NC). The switches that come with the EleksExtra are NC type therefore you need to set the default $5 GRBL code to ZERO ($5=0) the other GRBL settings you should look at are $20 through to $27 (see my default GRBL Code below), $22 is Home Switch Control so you need ensure that is set to '1' (the V1.1f firmware should set that value automatically). My GRBL code still needs a bit of tweaking for size of engraving area, bounce back and speeds etc.
I have my Mana SE board located at the rear and have set the X-axis switch on the left and Y-axis switch at bottom left. The GRBL setting $23 determines the location of the home switches and direction of travel see below:
$23=1 Top left home location.
$23=2 Bottom right of your work area to be the home location.
$23=3 Bottom left.
$23=4 Spindle down home location. (Z-Axis not used in my case)
I also posted asking about the blue switch but got no replies. Since getting the EleksExtra going I have found this has had no effect on the homing function in my particular case (only using X and Y).
$0=10 Step pulse, microseconds (10)
$1=25 Step idle delay, milliseconds (25)
$2=0 Step port invert, mask (0)
$3=3 Direction port invert, mask (0)
$4=0 Step enable invert, boolean (0)
$5=0 Limit pins invert, boolean (0)
$6=0 Probe pin invert, boolean (0)
$10=1 Status report, mask (1)
$11=0.010 Junction deviation, mm (0.020)
$12=0.002 Arc tolerance, mm (0.020)
$13=0 Report inches, boolean (0)
$20=0 Soft limits, boolean (0)
$21=0 Hard limits, boolean (0)
$22=1 Homing cycle, boolean (0)
$23=3 Homing dir invert, mask (0)
$24=100.000 Homing feed, mm/min (100.000)
$25=1000.000 Homing seek, mm/min (1000.000)
$26=250 Homing debounce, milliseconds (250)
$27=1.000 Homing pull-off, mm (1.000)
$30=255 Max spindle speed, RPM (255)
$31=0 Min spindle speed, RPM (0)
$32=1 Laser mode, boolean (1)
$100=80.000 X steps/mm (80.000)
$101=80.000 Y steps/mm (80.000)
$102=80.000 Z steps/mm (80.000)
$110=3000.000 X Max rate, mm/min (5000.000)
$111=3000.000 Y Max rate, mm/min (5000.000)
$112=3000.000 Z Max rate, mm/min (5000.000)
$120=200.000 X Acceleration, mm/sec^2 (800.000)
$121=200.000 Y Acceleration, mm/sec^2 (800.000)
$122=200.000 Z Acceleration, mm/sec^2 (5000.000)
$130=400.000 X Max travel, mm (400)
I hope this helps.