I came here to thank you from all my heart.
I have a Garmin Nuvi 255w bought in Italy.
It's an old model and some friend requested me to "speed it up" so, wrongly I decided to format it like any other tech device (after a proper back-up).
Not only I started to format it but the format was even interrupted by a random BSOD of my pc.
Fortunately the device could still operate with the fabric version of the software but the pc couldn't recognize it.
I tried this cure with a firmware downloaded from one of the websites listed above. Everything proceeded successfully but the device couldn't turn on past Garmin Logo.
So I decided to do the same procedure with the Gcd I had back-uped on my pc.
Everything works like a charm.
Million thanks to you and every other person who collaborated!!!