How can I fix the Magsafe battery pack not charging my iPhone?

I charged my magsafe battery pack overnight.. in the morning i saw green light blinking then i tured off the charger.. then put the magsafe on my iphone it wouldn’t charge my iphone & green light continuously blinking.. & my iphone is not charging by magsafe due to green light blinking without chargi the macksafe.. how to solve this problem ?