Make sure your using the right version. Also, after it is installed. Hold the power button for 2 seconds or so when powering on the xbox, see if that works.
make sure you have the right d0 and d1
http://www.apple-chip.com/applex_v/a...v_1_0__1_1.jpg
v1.0-v1.1, v1.2-1.4, and version 1.5 each have mildly different points to solder.