No worries - no one is in a hurry. Thanks for checking and sending me the file. I erased the chip (+checked via blank-button), opened your file, wrote it to the chip, veryfied it, hit exit, disconnected the clip, put the cmu board in the housing and connected the cmu to my bench setup (verified working with cx-5 cmu`s so far, wiring is not different to mx5 or m3 CMUs). But nothing happened, when I powered it. Just a black screen. Did the procedure incl. writing to the chip again, same result. Then I changed in your file at line 10000 the first values from FF to 00, but still nothing to see at the display. Then I connected a cx5-CMU and the display worked. Might it be, that the CX-5 display (build in dashboard, instead of on top of dashboard like at M3/MX-5/Miata) is not working with other CMUs? Or do I have to run the CMU in the car for some reason? My bench has a CX-5 display, old usb hub and a commander knob.
Your assumption, that the user of this CMU did something wrong might be partially right and wrong: The user does not know how to perform firmware updates and had the car at the dealership (Sept. 2020). They told him, that the latest firmware has been installed by them (so if something went wrong while installation, it was the fault of the dealership). And after 1-2 weeks after the said-to-be-update-by-dealership (not checked by user/customer) the display went black sometimes and then completely. Then a new CMU was sold/installed.
Or its not the SPI NOR chip, which lead to the non working CMU, but some other chip/condensator/cold soldering connection. But how to check all the connections at the CMU board? I have a multimeter and know how to use it, but these are so many connections.