Soldering points are complete different between 1.0-1.5 and 1.6's. If you did a 1.4 install on a 1.6, then it probably won't work.
Use this verion guide:
http://xbox-scene.com/versions.php
If it doesn't boot, then it could be the d0 or ground Usually if those are correct, any of the other wires not connected properly would result in frag.
I dislike solderless chips.
btw, make ure you ONLY install 1.6 bios if the xbox is 1.6