Ok. Not to insult you but I'll start at level 1. Here are some ideas I have for testing.
Let me know if this helps:
#1 - You have the freezer set to max cold, right?
#2 - The freezer works great when plugged into the wall and doesn't shut off, right?
#3 - Try taping the probe of the temp controller to a beer bottle in the keezer, insulate it with cardboard and more tape... still shutting off quickly?
#4 - The Temp controller is set to cooling (not heating cycle), right?
#5 - The Temp controller is set to max cold and it's still shutting off?
#6 - The +/- control is set to a very narrow margin? (like 1F not 10F)
Hope that helps you trouble shoot a little. I have a Johnson on my Keezer so I can't be more specific.
Last brew 9/10/16: Chinook, Centennial, Cascade IPA - 1.066 OG - 51% Pils / 46% 2 row / 3% 22.5L Honey Malt - US-05