Someone please explain software upgrade and why it takes so long? they started software upgrade today at about 10am and it failed at around 3pm.. so they are going to do it again tonight...

Why does a software upgrade take so long? for such a dedicated specific system shouldn't it be quicker. How is this thing connected? 9600 baud transfer rate? don't get me wrong.. if it needs that much time for safty's sake.. then fine, no problems here. But its 2 days less that i have my car.. and i can't have another weekend with this maroon chevy malabu