Hello,
Our application requires NXP firmware to be updated through UART from another host controller. Our configuration has a bootloader flashed at location 0x000 and application image flashed at 0xA000. In normal configuration without Flash security OTA is working fine and when Flash security (FSEC = BF) is enabled OTA Fails.
Please find attached the flash configuration where OTA is successful without Flash security.

Flash configuration where Flash Security is enabled with Backdoor key access and OTA Fails.

Please refer the attached failure logs.