I have just tried to do the downgrade on my AVIC-D1 since it's telling me "Please insert appropriate disc" and I was not able to complete it.
When I get to the force write part I go through the menus to do the system program and once I get to the language selection, all of them say [ NG ].
ie.
2. English US [ NG ]
I'm trying to use my 1.0 discs that I got with the unit. From what Pioneer told me, the previous owner may have used newer ones and since he did not give them to me, I can't use mine.
Here's the versions I found in the version check menu:
System Boot
