They can be tested when still in wafer form with a prober. All semiconductor manufactors normally run them to check their yields. These could be some really cheap chips that are normally high yielding and they do not probe them or only probe a few die. The company I worked for built all high value chips, so everything was 100% probed.MOdules populating does not mean vehicle is built, as I recall from time my modules showed and actual build date - it simply means, if I am not mistaken, that all parts are in the plant for assembly of said VIN.
Until chips are actually installed and powered up there would be no way to know if a chip is bad. Just like everything in the world, only a select few items from the production line (including chips) are pulled, tested and tossed
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