It is possible, however it can be a little "iffy".
Disclosure: DO NOT DO THIS! This is for informational purposes only
You can try to jump a good pack onto the bad pack to help "jump start" the cells to get them up high enough a charger can charge them. I have successfully done this on a balance board before, but know, it can burn traces in your board. The other way is one cell at a time. If you have bread board jumpers (male), you can put one in the negative, and start jumping one cell at a time.
When you do this, Or when "I" do this, I plug the negative in, them I plug in and immediately unplug the jumper on the positive side. This is to stop it from charging the cell too fast which can cause puffing.
It's dangerous, it's risky, I would do it outside on gravel or pavement and I do not suggest anyone do this. But, it's also a very expensive battery pack and sometimes, especially now days when a dollar is worth 10, it's worth it to ME to try to save a $200 pack....