Just charge them, and see if any of the packs are still usable.
If not, don't bother trying various cell recovery recipes found online. They never work. I've tried.
At most you can dismantle the packs and test each element individually. Usually only 10-20% of the elements are bad inside a pack, the rest of the elements are still usable. Replace only the most bad ones and thus you may end with a working battery pack. This is usually very time consuming, ideally requires a spot welder, and there is no guarantee the resulting pack will last for long. Expect the other cells to fail, too, sooner or later.