Hi Joe,
Unfortunately due to the way firmware is written to electronics, if the process is stopped during the firmware update before completion then the device is ‘bricked’ as there is no firmware or a corrupted firmware on the device. Firmware updates overwrite the original firmware data during the update so stopping the update leaves you with an unusable firmware and therefore an unusable device. The best you can do is talk to Samsung support about this issue but there is unfortunately not much you can do yourself to fix the problem.