cells might still be fine, I’m guessing that your BMS probably has a low voltage cutoff and wouldn’t let the cells discharge anymore hopefully. If the individual cells measure around 2.5v or more they might still be good depending on the manufacturer of them. HG2 cells for instance state that they should be used down to 2.0v so there is a very large range depending on the chemistry.
1.)measure individual parallel sections of the pack.
2.)use a bench power supply to charge the cells with a relatively low voltage 3.0v if they are 2.0-2.5v at around 1A or less of current(read the datasheet for the cells.)
3.)I would check the internal resistance if you have a meter otherwise plug it in outside and let it fully charge in a safe area, preferably concrete with a metal container you can put over the top.
TLDR: Go for it dude. just take safety precautions.
edit: my spelling is awful lol