I recently downloaded the Nuvi 660 firmware upgrade from the Garmin site to upgrade to v2.70. I did this as I read some other comments that the webupdater application has (in some cases) caused corruption.
I ran the firmware update as per the instructions from the Garmin website and two .bin files copied to the unit but the third file (I can't recall the extension) failed to copy with a file in use error. I could not work out a way to recover from this as the upgrade failed (not fully complete) and the only option was to reset the unit via the power button.
When the unit came back up again the following error came up on the screen:
"system software missing"
The Nuvi would not boot!
I contacted the local Garmin support rep on (02) 9844 6666 and I was given the following sequence to recover from this condition:
1. Power off the unit.
2. HOLD down the power button and you will see "Pre Boot Mode" appear on the lower part of the display. KEEP HOLDING the power button down and the display will flicker, do this until the pre boot mode message disappears. This seems to take a long time (60 seconds at least).
3. Once the pre boot mode message disappears release the power button and your device will perform some activites to recover from the above problem.
Apparently this sequence will only work with the above error. I hope this assists other if they encounter this problem.
I still don't know why the firmware upgrade process failed BUT after performing the above sequence I found that the firmware upgrade had actually worked (strange).
This is also my 3rd Nuvi 660 I did the web updater and it took out the bluetooth. I called tech support and we tried to load the original program back into the unit but it never would work. I returned the unit. The next unit was ok I did not connect it to the webupdater at all. I did use the blue tooth for my Blackberry phone. While using the phone all was ok until I hung up. then the unit would not find the satillettes at all. Then when I tried to reset it I got the same situation that you had. ,preboot code> Also when I tried to update it I got a file is corrupted. I returned it also. Now I have the third unit. I love the unit for navigation. I do not use the Bluetooth and do not hook it up to the internet at all. I am afraid that it will crash again.
Last week, I updated mu NUVI 660 to the latest software release. This was to get my Nuvi to recognize a Transcend 4GB SD card to play MP3 files for my trip to Baltimore.
It seemed to update fine, however it still did not see the SD card. I copied the files to the card from my notebook card reader first. That did not work. I erased the files and connected the Nuvi to the notebook to copy the files thru the Nuvi. This was agonizingly slow process. Must have only USB 1.1.
Now the unit is losing satellite signal and takes a very long time to find them. Driving Back from Baltimore it took 4 hours to find the satellites. Then it lost them again. The maps took a long time to display too.
I tried the reset button under the GPS antenna, No luck. I just did the power button reset as posted here and it is looking good so far. It fires right up and the maps display fast again.