Question, statement and (hopefully) a solution:
Question: Who is "they?"
Statement: The most likely reason for bad batteries is because a small piece of foil ruptures with shock and causes the two electrodes of the battery to touch, overheat, and create problems (i.e. exploding).
Solution: Unless you're really comfortable working with at-risk lithium batteries, I wouldn't work with it, and would carefully dispose of the battery properly. If the battery bends a fraction of a millimeter too much, you could rupture that same small piece of foil and start a chemical fire or explosion. This problem was only intensified with the S7 Edge as that foil simply failed too easily. You can get a new battery from a reputable brand like iFixit and use their replacement guides. You may need to also replace the screen adhesive.
Galaxy S7 Replacement Battery