Hard drive not recognized

Case:
1000GB mobile hard disk in the West, there is no reflection after powering.

Solution:
The engineer tested that the hard disk circuit board was damaged. After replacing the same type of circuit board, the hard disk motor rotated normally, but the magnetic head made an abnormal noise. It was confirmed that the magnetic head was penetrated due to excessive voltage and was damaged at the same time as the circuit.Replace the magnetic head, calibrate the magnetic head, and read the firmware module through the dust -free room. After the hard disk is normalized, the data mirror is made, and the data is 100%recovered successfully.