You probably don't want to hear this, but I'm going to confirm the above. Just as when someone experiences a bad TSOP flash, you'll need to install a modchip with a hacked BIOS to boot.
Modchips use BIOS replacement as their premise. My understanding is that the BIOS is one of the first things to load, second only to the MCPX. (BenJ, correct me if I'm wrong). The dashboard exploit obviously uses dashboard modidication as its premise, so it is factoring in far down the line with respect to the order of events during a boot.
Obviously you can't boot an EvoX disc because the Xbox will look at the disc first and it will see no reason to execute the unsigned XBE.
Install a mod, and make an EvoX boot disc. In the evox.ini, set JumpIfNoLink = No. Good luck, and post any more questions.