Samsung Hard drives that do not spin up after the power has been supplied can be diagnosed as PCB failure. Because data recovery service is very expensive, sometimes we would prefer to swap PCB ourselves.
To find a matching replacement PCB, you should find out the PCB number which is etched on the PCB(begin with BF41-), see the following image:
Samsung Hard Drive PCB Circuit Boards
What is Samsung HDD PCB’s BIOS Chip?
All of the 8pins (4 pins on each sides) with 25P05VP, 25P10VP, 25F512, 25F1024, 25F1024AN, SST25VF512, SST25VF010, etc. are the BIOS chip. It is easy to be found because there are not many 8pins chips on the PCB.
In most cases, you should exchange the BIOS before you swap hard drive pcb. You should have certain technique.