Originally Posted by JAM MaxAmps

If your using Deans plugs Clean the inside of the plugs. Scrape them out with a Number 11 X-acto blade or a small thin screw driver. Solder flux can and does seep through from the back side when we install them. We try to clean the plugs but sometimes the remaining flux hasn't cured at that point and dries later. It forms a film on the contacts that is like wax. It will not allow for contact and you may get the error. We check all packs after they are built on a charger in house so chances of you getting a defective battery are very slim.

Jason