The software is perfect. I have many such boards
and it runs perfectly.

again "the fact that something works does not prove that it is right"

example: a circuit will work if a cpacitor is >1.2uF, which you did not know. You specified a capacitor of 1uF with the normal tolerance of +100/-20%. Your circuit runs fine. A year later you build more that do not work.
example: you use a RAM that at its worst case spec will not meet the timing requirement but the RAMs you got were colsert to typical specs.
example: The software is fine unless a serial package is checksum bad. That did not happen so "The software is perfect".

OK all, let us not hear again about perfect stuff that does not work

Erik