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.