I think you need to clear the boot flag and then reset...
you may also need to pull the AC plug for it to take place...
don't do it until someone else confirms these steps as my Z is now on it's deathbed after screwing around in the Diag Menu. (you've been warned)
I've looked and looked and not been able to find any documentation on exactly how to use this menu (or to properly get out of it)
good luck
Haha - yeah, I've been warned ;-) Funny how I did most of my reading about this menu *AFTER* dicking around with it for a while. Who knows - I may have bricked it myself... Ah well, I learn better that way.
I'll look again for a boot flag to clear this afternoon. I saw a post about removing the battery and leaving the unit unplugged for 24 hours, so I'm letting it sit for the moment. If that doesn't work (and I'm not all that hopeful - it seems to easy), then I'll look for the boot flag.
Thanks for the tip.