I had purchased an update online a few years ago from a selller that I regularly purchased updates for my friend and family. We have this avic90dvd system paired with an avhp7500dvd system for many years. Unfortunately the update did'nt work and now the system is asking for for the appropiate disc. I have done restores to other systems, eg Avic d3, and would like to know iif this is posible with the Avic-90dvd. Thanks for any help!