Try updating the firmware (via SD card) if this works then most likely the controller board is OK. It the device throws the SC672 then you'll need to...
I would suggest to not let it do firmware with the finisher attached. It could work like the FS534 working instead of the FS536 on the 8 series but
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You have got me curious. What are you trying to do? The devtank will discard excess developer through the waste port. I would guess about a teaspoon...