Google how to bring a dead battery back alive. There are numerous videos showing how plugging the charger in, then unplugging it, then plugging it back in, and repeating actually gets the charger to charge the battery once again. Mine are still good so I haven’t tried it yet, but you might want to take a look at them and see if it works for you.
Check out Home Depot’s online deals. They have several Milwaukee tools that come with a free battery. I’ve purchased the M12 1000 lumen light with a free 2.0 battery for the same price as the tool-only unit, which showed up yesterday (2-day shipping) and ordered the 1250 lumen M12 Searchlight yesterday that comes with a 3.0 Red Lithium battery For only $20 more that the bare tool.