Hi I am sorry to hear that.
How old is your Garmin?
Thank you for that information.
Unfortunately this problem indicates a failed memory IC in the Garmin;-(
It likely happened due to a power surge during the outage, its a common issue I see all the time with these.
I wish I had better news for you on this I really do. But this woudl require service.
There is a great site for that through Garmin if you decide to have it fixed, I will list that below for you.
If this were me, I woudl likley just replace the GPS unit because the new ones have a lot of new features and cost about the same as the repair would.
But you can check on the repair direction anyway?
Please contact Garmin Repair: http://www8.garmin.com/support/outofwarranty.html
Or simply call:(###) ###-####or(###) ###-####
In any case, I will stick with you until this is complete.
Please rate my service thus far.
Also it is the only way I am credited for my time and expertise with you.
Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.
Then you can reach me by simply replying to this message anytime.
Thank you and have a great day!