I purchased a PowerCore 13000 in Oct. 2016. As of last week it was charging devices just fine. Unfortunately, it stopped this week. It appears to have a full charge as all 4 lights are illuminated when a micro USB is plugged into the input. When trying to charge a device, each light will light up in succession and then turn off and it will not charge various devices. Multiple working cables (lightning & micro USB) have been used to try to charge devices with the same result.
It is probbably dead from old age, but there is a small chance it has got confused.
Connect its input with output and press the power button, leave like that for a few seconds.