SEEED Studio SAMD-21

Hello, I purchase a SEEEd Studio SAMD-21 a few months ago and I used it for a few weeks and it worked fine, then I stopped using it for a little while, and when I tried using it again today it doesn't show up when I plug it into my Macbook. I have tried resetting it and that makes it connect for about 5 minutes and then it automatically disconnects. Does anyone know how to fix this