Depends on what caused the hdd to fail. If it was the PCB, for example - that would have been 100% recoverable 20 years ago, but for the past couple decades the interleave/alignment data is stored on the pcb and without the original, a drive just looks blank to a new PCB. If the drive supported on-device encryption, and the pcb failed, you can eventually put the drive back in service but your data is gone.
Motors, bearings, and head actuators can usually be repaired enough to salvage data in a competent lab. Also certain failures caused by firmware flaws can be recovered from (I have done this myself).
Depends on what caused the hdd to fail. If it was the PCB, for example - that would have been 100% recoverable 20 years ago, but for the past couple decades the interleave/alignment data is stored on the pcb and without the original, a drive just looks blank to a new PCB. If the drive supported on-device encryption, and the pcb failed, you can eventually put the drive back in service but your data is gone.
Motors, bearings, and head actuators can usually be repaired enough to salvage data in a competent lab. Also certain failures caused by firmware flaws can be recovered from (I have done this myself).