You might have to do what the tutorial tells you to do, since any different connection setups on the USB-SPI and Xbox 360 will lead to different problems. The solderless pins are the best way to go. If you want to solder, you have to cleanup any solder that may have dried. It will cause the circuit to overlap, which will cause all the solder points to combine and not make a separate connection.
I have given the correct order of everything for the solderless addon method or the solder method here -
http://www.tiaowiki.com/forums/xbox-360-hardware-talk/nandpro-2-0e-jtag-starting-checklist-(all-windows)/ You might want to consider starting over from scratch and rechecking connections.
Also, get rid of overlapping wires and overlapping solder. Remember you can use a multimeter to test the solder points.
