Unit is completely blackout!

Are you using the correct USB cable?

Can you turn it on if the USB cable is unplugged?

Try sliding the power switch to the on position and holding it there for at least 10 seconds. That should force a reset without losing your data.

That happened to my 255 last week. It locked up when connecting it to the USB. I thought I had "bricked" the unit because I couldn't get it to turn on no matter what I tried. After several tries, the reset button on the bottom of the unit finally got it going again.

I tried a lots different things but the unit still not working and I send unit back to the store to fix the problem and I hope I will get my unit back may be next week.

Thank you all for helping.

Call Garmin support !

Did you try going in to windows explorer to see if it recognizes the Garmin? Also, try another usb on your computer to see if you get the same results.

send it back, garmin has good support

Yes, I did try to go windows explorer and I also try on different usb and on different computer but it still not recognize my Garmin. I did send my unit back to fix and they said it take about 4-8 weeks. Now, I have to wait...

Thanks for giving me some advices

4 TO 8 WEEKS??
That doesnt sound right...
When I sent my 660 back for a blown speaker it only took 2 weeks (and even then..it was delayed because of some misinformation they had)

Mine was out of warranty, called them, they gave me an RMA. Got a refurbished back less than 2 weeks later--with newer maps than I sent in.

Finally, I got my GPS back and I think they did a good job, they fix the problem and also load a 2009 map to my GPS.