Well I've really managed to screw things up now.
Seemed I was stuck at Nitro 0.9.5 no matter after running Smart Installer = same issue
Finally followed some steps here via ssh: http://wiki.awkwardtv.org/wiki/NitoTV_Take_2
Managed to get the Smart Installer to run without errors.
sudo mount -uw /
sudo touch /.readwrite
sudo dd if=/dev/disk0s2 of=recovery.dmg bs=1m
Tried to update "Flash" = same error like it can't find a file (Screen blinks fast off so can't really tell what it's saying.)
At the bottom of Settings I believe in "Nitro" I now noticed a selection to (Update Nitro 1.0)
Did that and the unit rebooted.
Now everytime I try to scroll past the (Launcher) selection on the main menu in ATV, upon it trying to select/highlight Nitro, the whole system crashes with:
An error occured.
Press Play/Pause to restart your Apple TV.
So I do this and it reboots with same issue. Even tried unplugging and re-powering to no avail.
No idea how to fix this now