I have tried updating the map using Garmin Express several times and despite Garmin Express saying that it has been updated successfully without any errors but 'no detailed map' or 'not unlocked' errors on Nuvi 2508 when I powered it on.
My friend gave it to me because of the reason above and he had given up on it. Using his original e-mail address made no difference at all. On both machines - Mac and Windows. At the moment, I'm using Windows version of Garmin Express. Using the original USB cable it came with and also one of my spare cable as well.
The box it came in, has 'Free Lifetime Maps & Digital traffic' label on it.
What is the reason for that?