I know this is an old topic but are you sure you are seeing the hot/cold code, Dash dot dot dash dot dot, or was it the replace pack, dot dot dot... I know that when I have been working my 18Vs hard and I put it on the charger I will get the hot/ cold message. If you're strapped for cash you can try to repair the battery by isolating the bad cell and "jumpstart" the cell from an adjacent cell or replace the cells all together. There are how to's on the You Tube. I'm not sure how cost effective this is but it can be an option to explore.