Hi
Booting from serial NOR is controlled by BOOT_CFG[4:7] - pins GPIO_B0_08..GPIO_B0_11, which should be '0' at reset. There are other pins controlling some further details too.
If these are not defines like this the processor will try booting from other sources.
In case the HW is not allowing t to boot as required and can't be modified to do so you can connect in ISP mode and program eFUSEs to override it checking the pins and force the mode that you require.
Regards
Mark
[uTasker project developer for Kinetis and i.MX RT]
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