HDD platter inspection is a complicated process that requires accuracy and attention to detail.
In our recent case, the drive has suffered from a head crash. Before submitting to us, the customer has removed the HDD lid to check the internal parts.
There were visible debris and microscopic circular scratches on the surface. Circular scratching means that the customer has tried to run the HDD at least once after the head crash.
Partial data recovery was possible from this hard drive, which we did, and we returned all restored data to the client.