Hi,
Thanks for this! I was in exactly the same position, Bought an Avic 920BT on eBay. i didn't fit it for months as I was working on the engine. When I came to fit it I discovered it had a password. I contacted the seller and he was helpful giving me loads to try, but he couldn't remember what it was.
My search brought me here and a quick download, print the instructions, rush out to the car and it's fixed
BTW his guesses were very close, It was his DOB, but all numbers and no words, so I know it's not a knock off!!
Thanks very much for your help.