It doesn't reenter a BFU state, but it requires a passcode for the next unlock.
replyIt's close enough, because (most of) the encryption keys are wiped from memory every time the device is locked, and this action makes the secure enclave require PIN authentication to release them again.
reply> It's close enough
replyNot really, because tools like Cellbrite are more limited with BFU, hence the manual informing LEO to keep (locked) devices charged, amd the countermeasures being iOS forcefully rebooting devices that have been locked for too long.
There is a way now to force BFU from a phone that is turned on, I can't remember the sequence
replyIt’s called restarting the phone.
replyEh? BFU ("before first unlock") is, by definition, the state that a phone is in when it is turned on. There's no need to "force" it.
replyIf you mean forcing an iOS device out of BFU, that's impossible. The device's storage is encrypted using a key derived from the user's passcode. That key is only available once the user has unlocked the device once, using their passcode.