In most cases, if the soybeans were dried on the plants, you should be able to just thrash the plants & pods against the side of a very tall container (such as a trash can or deep tub). The pods should shatter, releasing the seeds. Expect a few to be expelled violently. You could also wrap the plants (or loose pods) in a sheet or pillow case, and either step on them, or beat them lightly against the floor. Unless you go full Rambo crazy beating them, the seeds should be undamaged. Threshing is best done in an open area, unless you like playing hide & seek with energetic escapees.
Most of my surviving soybeans were harvested by cutting the plants off at the ground. They are drying in tubs on my screened patio, until all stems & pods have dried. Before shelling them, I bring the tub indoors & place the soybeans under a ceiling fan for a day or two to dry down further. Depending upon my mood, I then either shell the pods by hand, or thresh them by beating the whole plant against the side of the tub. More often than not, I choose to hand shell.
The toughest soybean pods (or for that matter, almost any tough bean pod) can usually be opened more easily if given a slight twist. I've got a couple varieties that are very hard to shell; those I'll probably walk on to either break the beans free, or loosen them for hand shelling. When hand shelling, it is usually easier to squeeze the stem end on the seams while putting pressure on the blossom end. Practice makes perfect.