Well, another day wasted trying to connect the electronics. I must say that I don't have much admiration for the state of commercial RepRap kit vendors. Nothing seems to work well together. If I didn't happen to have tools and supplies for low voltage wiring I wouldn't have even got this far with my Mendel... which isn't even done.
There are very few complete instructions on how to build a hot end. Most of the instructions from kit makers leave out building the hot end and connecting the power supply. If you have the knowledge to build a Mendel, why not share that with your customers? How long does it take to type up a paragraph and add a few photos - perhaps even a video showing step by step how to put one together!
The thought of complete instructions shocks most kit vendors and enrages that community that you would actually critique a for profit business. The door is wide open for a commercial RepRap vendor to take over the entire space by supplying parts that work together, e-mail support, and instructions. Without those things, your money is probably better spent sourcing parts on your own.