NEW Anker PowerCore+ 26800 PD -- How do I know it's charging, won't hold charge

Just purchased Anker PowerCore+ 26800 PD. Plugged it in using provided charger that came with it. It blinks around the circle lights about three times before going dark.

When I plug it in to my macbook pro it literally only charges the computer for about 5 mins then shuts off.

I’ve left the powerbank unplugged overnight, how can I make sure I am charging it when it’s plugged into the wall, and how do I know it’s done?