Why is my Arduino still working?
The Arduino is tougher than it looks. ;-) Or maybe you were just lucky.

The exact point of failure of an IC is hard to predict, because of part
to part variations, and because it can depend on many uncontrolled
factors (duration of fault, temperature, voltages and currents on other
pins, part history...). Then, the absolute maximum ratings are not the
predicted point of failure. They are rather a lower bound:


The part should not fail if you do not exceed the ratings
it may fail anywhere beyond those limits.


Time is, however, also a factor. The manufacturer says that operating
the part close to the limits for an extended period may shorten its
lifespan.