When you say "try to turn the platters" does that mean that you do not hear the drive spinning at all? If in fact the drive is not spinning up and you hear the "clap clap clap" sound it appears to be a case of head stiction. In this situation there is often some media damage where the heads are stuck to the platters and, sometimes head damage as well. If you open the drive the answer will be apparent to you. Be forewarned: delicacy is called for.