Nuvi 660 quit working

My nuvi 660 stopped receiving satellite signals in the middle of a road trip
yesterday. It was working great and then all of a sudden just lost
connection with all satellites. We drove for another 2.5 hours and it never
reconnected. It still won't connect this morning. I assume my antenna
circuitry has broken. I tried the reset button on the back but no change in
behavior. It's only 4 months old and I'm going to call support when they
open this morning but thought I'd check and see if anyone else has run into
this problem and what they did to fix it.

Have you tried update the software version for your unit

http://www8.garmin.com/support/collection.jsp?product=010-00540-00

http://www.globalpositioningsystems.co.uk/subscribe.php

Yes, I updated the software before the road trip. All software is up to
date.

Ok another soloution

MAINTENANCE MODE:
Step 1. Turn your Nuvi unit off, remove any SD cards from the SD card
slot and make sure that the unit is not plugged into any computer.
Step 2. Place a fingertip on the upper left hand corner of the touch
screen and keep it there while turning the unit on, a prompt should
read " Do you really want to start in maintenance mode?"
Step 3. Select the yes button.
Step 4. Enter your PIN if enabled.
Step 5. Main Maintenance Mode screen should have 4 selections:
System information
View Diagnostics
Clear User data
Clear Waypoints

Choose View Diagnostics, to check and see if your GPS is broken

Wow, a maintenance mode. That's good to know. My diagnostics page says

Abnormal Powerdown (repeated 5 times)

Then it says
RTL Trap 07-Oct-07
RTL Trap 06-Oct-07
... Several more of these back to 23-Jun-07

Nothing about the GPS. These are the only entries shown.