[mmebane]

It pretty much has to be either a service mode or a developer back door. I'd love to know for sure. Maybe a leak some day will satisfy my curiosity.

[jtvjan]

In the presentation made when it was discovered[0] they said: “The NTR cartridge was likely meant to be used for either the factory setup or as a means of recovering bricked NANDs. However, we'll never know for sure.”

[0]: https://sciresm.github.io/33-and-a-half-c3/