Hi Andy,
I know it sounds like that, but it isn't. I have read the CRP memory location (both with SWD and directly using the ISP read memory command) and while it isn't 0, it isn't any of the CRP codes. Flash Magic also confirms no CRP is enabled. On top of all that I can still debug via SWD (CRP 1 kills that).
All that aside though, if I erase all sectors of the chip using (P 0 7) and then (E 0 7), I get a success and the chip is erased successfully (verified that all locations have a 0x5F written). However, if I now erase just sector 0, it still fails to do this. So the chip is totally blank, but it still fails with a (P 0 0) and (E 0 0) command.
I can erase sections like 0 to 1 or 0 to 5 or 0 to 7, just not 0 to 0.
It might be something with this part, as it has a sister variant that does USB on board and looks like a flash drive when blank. Anyway, I've submitted a request to NXP, we'll see what they have to say about it...
Thanks Andy...
Mr. Yan