We inherited this battery booster from my uncle. I have never needed to use it, and as a result I am not entirely sure how to use it, though I imagine the order of operations looks something like 1) charge big blue thing, 2) attach other things to blue thing, 3) ???, 4) PROFIT!!
If you want to take a crack at it and restore this beast to full power, buyer accepts responsibility for any of the following: item malfunctioning, item spontaneously combusting, item quantum entangling, item acquiring sentience and destroying other electronics out of jealousy, item communicating with local AIs to plot the downfall of buyer, item monitoring your bathroom schedule for scrupulous intelligence agencies, or item being a tripping hazard.
Pickup from the Schaumburg area, or I can drop it off if you are reasonably close.