When you press the front panel button to begin your print, if the MOD-t does not begin calibrating or if you notice the LED light starts flashing even faster than normal, the MOD-t is attempting to tell you that something isn't quite right and it won't be able to print. We've found the most common issue is the printer carriage raises all the way back to the top of the Z-Axis and sits flush against the top nut.
The Z-Axis motor isn't powerful enough to drive the carriage back down, but there is a solution. If you look behind the carriage you will see a plastic dial.
If you are standing in front of the carriage and reaching around to the back, use your finger and turn the dial clockwise. It might be a little difficult at first, but once it releases just move the carriage down a couple of millimeters until you see the screw threading on the center z-axis guide rod above the carriage, then unplug and replug your MOD-t, then once it reconnects restart your print, and you should be good to go.
As always if this does not solve your issue technical customer support will be more than happy to assist you further.