FYI: If you're updating a MEN2 unit and the firmware SD card is being rejected with an "SD/card reader error", try starting the update from the extended setup/service menu instead of using the normal "Update software" option under Setup. On my 2019 Skoda Fabia with MEN2_EU_SKGPx_P7381L / MU 8740 / HW 690, the SD card worked perfectly for playing MP3 files, but the normal software update menu kept reporting an SD/card reader error. The solution was to press and hold the SETUP button for about 5 seconds to enter the extended setup menu and start the firmware update from there. The exact same SD card and firmware files were then detected correctly, and the update to MEN2_EU_SKGPx_P0080L / MU 8755 completed successfully. The update also appears to have fixed my CarPlay audio crackling/distortion, which previously started after about 30–40 seconds of playback. Hopefully this saves someone else from repeatedly reformatting SD cards or assuming their card reader is faulty.