OK heres the deal. I will try to simplify this matter. When you turn on your xbox, the ms bios will load the file "xboxdash.xbe" This is the ms dashboard. When you install a mod chip, you have a number of options, the easiest one being - download a bios that has a different boot sequence. (I.E. The Xecuter 2 bios). These bios's will boot the executable (the xboxdash.xbe file) in a different order. Example: My Xecuter 2 bios will boot "evoxdash.xbe" first, then if that is not found it will load up "xboxdash.xbe" Now, on the root of my C drive, I installed Evox. I named the xbe file "evoxdash.xbe" and left the ms one named "xboxdash.xbe" What this does is allow me to turn off my switch and load up the ms bios. If i turn the switch on, my xecutor 2 bios will load up "evoxdash.xbe" becasue that is first in the boot sequence, which is evox. If i turn the switch off, the ms bios will load "xboxdash.xbe" which is the ms dashboard. I am completly safe from the update.xbe file. When you run the update.xbe file it will update your "xboxdash.xbe" file.
Now here is where people will nuke their dash.
1. they install a modchip, or use an exploit or whatever other means to mod their xbox
2. they install their new dash, and it is named "xboxdash.xbe" (their ms-dash might be renamed to "msdash.xbe" or something else
3. they run the update.xbe file, by downloading new maps, content, etc..
4. the update.xbe file overwrites the previous "xboxdash.xbe" file (which is your dash) with a new ms dash
5. they turn on the xbox and the MS dash loads up even with the chip enabled.
Now here is how to fix it.
You are still running your downloaded bios. The update did not affect this at all. You should still be able to run homebrew code (evox,avalaunch, etc..)
1.turn on the xbox
2.insert an evox boot disk ( you should still be running your bios at this point and therefor be able to read the evox disk)
3.ftp to your xbox, rename your ms dash (xboxdash.xbe) file to something else and reupload your dash and name it "xboxdash.xbe"
4.eject the evox disk
5.restart the xbox
you should be fine again at this point
to prevent this from happening agian
1. flash your bios with one that supports a new boot sequence
2. Name your dash to one of the options in the boot order before "xboxdash.xbe"
3. Name your ms-dash back to "xboxdash.xbe"
Sorry for the long post, hope this clarifies the problem for some people