A PCB swap should be fine. Just power up the bad drive with the new PCB - if the drive comes up then you should be fine. If the drive starts knocking, then pcb is probably not compatible or internal chip may have also blown. On some occasions there is info on the PCB board that contains info that is directly tied to the HDD, so a swap will not work and may cause more damage. The only thing to do then is to replace the chip and reflash the ROM. If you have a chip extracting tool, and the right soldering equipment, you could very well do this, too. Use an exact replica of the HDD, though.
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