Hello,
With reference to iMXRT1170 EVK - We need couple of information:
1. Does the EVK comes with flashloader(signed/unsigned)? If yes, please share details to modify the existing flashloader.
2. What are the tools required to bring-up the EVK?
iMXRT1170
What kind of flashloader do you mean here?
There is an 2nd flashloader in \SDK_2_12_1_MIMXRT1170-EVK\boards\evkmimxrt1170\bootloader_examples\flashloader. it can be used to flash external NVMs. this flashloader should be loaded by On-chip bootROM first.
2. You can download SDK examples by on-board CMSIS-DAP debugger, or MCUXpresso Secure Provisioning tool or MCUBootUtility tool.