I tried out my cart today. It works fine and holds a save, and works with the latest version of the software. I think it's alright, just needed a battery recharge.
Thank you very much for your help.
I tried charging it. I still get the error message.
The weird part is that the data on all the rest of my games is intact. Is the cart really broken?
EDIT: It's working with version 5.5 of the software. Is my cart all right then?