Hello,
We do no see any link between bad DCF configuration and key activation.
That's hard to comment. Yes, there should not be directly, but try to do mode transition to mode with IRC (not PLL). I am quite sure it will work. In BIST DCFs you also configure PLL so it is possible.
But if you reconfigure it again then the DCF configuration is overwritten.
petervlna_0-1660025617813.png
I would test failing chip in NXP evaluation board first as there could be some HW issue.
The question is was the sample working (mode transition to mode with PLL) before you program DCFs or not?
"debug port fail" whn trying to write the second key that activates the DRUN mode
Hmm, how about reset line? Sudden loss of debug looks like voltage issue to me. Have a look at HDD_HV and VDD_LV and also reset line while this event occur to see if there is not any other problem.
Best regards,
Peter