Forerunner 645 won't charge

I have been using my Garmin Forerunner 645 for about 4 months. This morning, when I tried to charge it, nothing happened. The battery was about 2%. I turned it off while connected to the cable and it still doesn't charge. I have blue/green triangle blinking alternately with the charging icon on the screen but it won't turn on and charge. What should I do?