Lets see what we can do here.
If you have any mechasasult downloaded content, that can muck up the operation of the exploit, so use the MS dash (boot with no disk in) to remove ALL mechassault savegames, including the linux one. Infact, do this anyway.
Then get the original mechassault_with_EVOX savegame from "the usual places" and get that on your HD using your memorycard and run that.
That should run a basic version of evox from the savegame folder, not the bios loader or anything on the HD.
Then you can FTP in and remove all the crazy stuff from the HD and start again.
I take it you havent fannied about with any font files or audio files, if so, good. The whole point of this savegame method is to avoid having to do that.
Also, on which HD (c: e: etc) and directory did you put Evox? are you sure you correctly modified and saved the bios to point to this? If not, when the bios loader loads, it'll crash as you said.
What you have to do is get the bastard cleaned up, so we can get it working correctly from scratch.
Dammit, I'm gonna make up a pre-setup download tonight for this exploit, cause so many people are having probs with all the setup stages...
#Wonderdog