Just signed up to AVIC411 ...
WOW, talk about easy !
Just got back from a trip OS (3 months), I disconnected the battery as the immobilizer tends to drain the battery.
Didn't think about the radio ... re-connected the battery, and ERRR ... radio needs code.
As I bought the car 2nd hand, I didn't have the code (and not in any of the doc's that came with the car).
Google brought me here - did the small SD card thing, and BINGO ! - radio back on ! - SO EASY TO DO - MANY THANKS !!!!!