If you like the unit and how it operates it may be a good idea to keep using it and see if it is going to be a persistent problem. Or maybe just one of those glich's that happens to electronics from time to time.
I am only speaking for myself but if it was mine I would give it another chance. You may be able to get an interface cable and hook it up to a desk top and reload or maybe even update the software from the hummingbird website. I used to run birds all the time and was able to update from their website. I would check their web page and see if that is still available. Just a thought.