Hi Jason. Sometimes you can revive a "bad battery" by manually charging the battery with a variable voltage power supply. In this case you have a 18.5v battery which is operating at 17v. You know that the battery pack is composed of at least (5) 18650 lithium ion cells in series. Voltage adds in series. 18650 cells have a nominal voltage of 3.7v (3.7*5 = 18.5v). Most 18650 cells have a charging voltage of 4.2v. If you charge the pack at 21v (4.2*5=21) or just slightly higher (~21.5v), you should be able to boost the nominal voltage of the pack closer to the desired 18.5v. I have found that manually charging a "bad battery" with a variable power supply for 10-15min will bring up the pack to a level where the genuine drill power supplies will be able to recognize and charge the battery pack again.
Good luck.