Assuming Rivian does know embedded 101, my guess is that the infotainment system is running Android and the watchdog reported all green once the system services

Assuming Rivian does know embedded 101, my guess is that the infotainment system is running Android and the watchdog reported all green once the system services all came online and that it doesn't actually check whether the application layer is really working because, as you know, that would require the watchdog to run a full regression suite before giving the okay, which isn’t practical. Since the update swapped the system to an internal dev cert, they cant push an immediate update to change the boot args because the management plane daemon won’t connect to the C&C server, or it can but the blob they push wouldn’t pass signature validation, or the TEE won’t unlock the device keys because the roots changed. Whatever the case, someone has to go blow a fuse and re-flash the thing, or at least rewrite the boot args via serial. Just a guess. If it is the most likely “management plane TLS certs” issue, I bet the watchdog won’t confirm the new boot args until the command dispatch daemon gets a pong from the C&C server moving forward (: