I am asking this for customers.
This is in production for more than one year.
The customer reported that end customers returned several units, and they found the codes of the fail units are different than those of the normal ones.
It's said the fail units could be used first for some time and then failed.
After being programmed, the returned fail units can work well again.
The user does not use any about firmware update, nor MPU (memory protection unit), nor data logging.
Do you have any suggestion or comment for us to support them to find out the root cause?
In the same time, we will check how their production line verifies codes integrity before shipping out in this case.