In my previous job I did failure analysis for returned ASICs for a high volume commercial application. As the parent says in fact because a modern ASIC has str

In my previous job I did failure analysis for returned ASICs for a high volume commercial application. As the parent says in fact because a modern ASIC has structural coverage with built in self test for the overwhelming majority of digital circuits, you don't ship a lot of parts with bad transistors. The vast majority of ASICs that I saw that were returned had failed due to electrical over stress, which is polite way of saying the customer blew up the part. But even more to the point, in modern electronics the ratio of problems caused by either software or assembly level issues is very high compared to ASIC level hw problems. High volume ASICs are designed with relatively large margins to ensure good product yield. Further the cost of investigating and root causing an issue to the transistor level is very high, that unless you have measurable trend defect rate, any actual random failure not related to design would probably be attributed to something else first. That is not to say that there are no HW design level issues with ASICs, but generally when they are discovered you would try and change the low level software to either make the problem not happen ever, or make it very very infrequent. You might also simply screen (test) the parts so you don't ship any that exhibit the undesired behavior. So it's not that such an event that the OP mentions can never happen, it's just that it's so infrequent compared to all the other types of problems that can happen in modern electronics that unless you have a very specific reason to believe it's being caused by hardware you would never be able to differentiate it from a random software bug.