if it is IDE try sticking it into a pc, partition and format it that way. I have done that in the past to fix dead Amiga drives. For SCSI I have connect it to a Phase 5 card with the power plug out. Power up the machine, load SCSI prefs, plug in HD and rescan the SCSI bus so the system sees the wrecked drive.
now you reinstall drive. that should recover the drive.
