The program is simply a timer program that makes an LED blink. It runs normally on an unencrypted board, but it doesn't run on an encrypted board after encryption. I don't know how to troubleshoot this. The J-Link can't connect either, making troubleshooting even more difficult. I'm using AXF or HEX image files. In the program used by FDCB, because the DQS pin is used, QSPI is set to 50M, and CSStepUp/Hold is set to 2. 
Hi @ccc_clive ,
I noticed you're using OTPMK, which is the SNVS key, as the key. However, this key is only valid when HAB is closed; otherwise, it's all zeros. Try the signed encrypted XIP mode to see if you get a different result.
Additionally, our experts have discussed similar situations in previous articles; for details, please refer to "If i.MXRT1xxx fails to start offline, please first check the SRC_SBMRx register".
Best Regards,
Kan
Hi @ccc_clive ,
Can you change the board's boot mode to serial download? If so, use SPT or MCUBootUtilities to perform a mass erase and see if you can re-flash the image.
Best Regards,
Kan