18650 battery after a short circuit - to throw it away or not?

Question

Rechargeable batteries

I just accidentally shorted a Samsung 18650 jar, it's unprotected. I pulled it out of a non-working powerbank and decided to immediately insulate the wires welded to it with heat shrink.
While I was seating the minus one, I did not notice how the plus one touched the minus in another place.
If I had started with a plus, nothing would have happened.
He got a pretty bad burn on his finger.
The jar cooled down instantly and shows 4.2 V as before.
Now I don’t know if I can use it or is it better to throw it away?
Is there a risk of fire during storage, discharging, charging?
Important: the bank has no protection.

Answer 1

The jar cooled down instantly and shows 4.2 V as before.

No-load voltage says little about battery health.
If the overload was not too long, then she might have survived, but I would not risk it.

Answer 2

In my opinion, in your situation, the most critical parameter is not voltage, but internal resistance and especially capacitance. You can measure them with a fairly widespread IMAX B6 device (and not only with it). To measure capacitance accurately, do it according to strict rules: first a full charge, then a measuring full discharge, and finally a partial charge for storage. You can measure the resistance both on a discharged element and on a charged one - it will be pretty different, you don’t need to be afraid of this. Then, in the same order, measure the adjacent (non-short) elements of this battery, for comparison.
If there is no particular difference in these parameters between the shortened jar and the rest, well, then it survived this cataclysm, and it can be used further (this has happened in my practice). It is possible that the short man affected the resource of this can (the number of charge-discharge cycles) - but this cannot be immediately determined, it is recognized only in long-term operation.