Hello & Welcome to Just Answer,
Sorry I didn't see your question earlier and to hear of any issue you are having with your device.
To help you with this issue, may I ask:
1) The FULL Model Number of the device you are working with? I only ask because there are a few "660" models of Garmin devices.
2) The AGE of the device?
3) Have you EVER added memory to your device?
P.S. Please close out any "offers" you may see on your side of this system.