[pilif]

As far as I understand, there's still the hardware key combination to put the device into DFU mode. In that mode it can still be connected to and a new firmware can be written, but no access to the data is possible.

So in order to un-brick an old device sitting around, you put it into DFU mode (the key combination varies from device to device) and restore it that way.

Of course you don't ever get your data back, but that's totally the expected behaviour.

[Matt3o12_]

Do you have any source for that information? I am very interested in that as well but couldn't find any information regarding that so far.

I have always thought (though without any source) that they re-flashed the iPhone by putting it into the DFU mode (and tricking the iPhone bootloader into accepting their key) and then just brute force the key.

[ghostly_s]

There is no scenario which allows re-flashing a device from DFU while retaining user data. This only appears to work in typical user scenarios because iCloud or iTunes creates a backup from the unencrypted device as a first step before flashing it.

[sdtransier]

That makes sense that DFU would still work, since that would let the data continue to be protected and wiped.