On my F700 I used the method in this thread to upgrade to 4.01 hybrid. 

The install went smooth, it was time to boot back into testmode, but it wouldn't for whatever reason. Perhaps tesmode 2.3 doesn't support 4.0? 

The next wall I ran into was it said my old maps were out of date in a window ontop of the splash screen. So I hit OK and it hung on a different spash screen that said Sound.Vision.Soul with the word 'LANGUAGES' at the bottom right of the screen. 

I couldn't get past that screen, and after a few min it rebooted on it's own.

So I figured I'd go back and install the original software with the backup SD that I made, which also went smoothly, yet I still can't boot into safemode and when I attempt to do a normal boot it hangs on the splash screen and resets. I've gone back and forth with the same results.

I've searched avic411 for the past couple hours, but every lead is a dead end, broken links and it's gotten me nowhere.

Does anyone know what I should do, whether it be upgrade to the EU version 3.x/4.x or reinstall the original software from 2009?

thanks for the help

I just put TESTMODE only on an SD and it booted into testmode. So I have that going for me.

I'm attempting to replace the files from my original 'My Flash Disk' backup folder. 

We'll see what happens.

Any other ideas what I should do?

I was able to get it running 2.006 

Now I just need some help from those who know this unit. 

NM. I got 4.01 working fine.