This worries me. By "sounds like a laser", you mean the charging circuits of the Laser as lasers are silent in operation...

But... the "grunt" and "gears petering down", that is a bad sign. Once a hard drive starts up, it remains running, to it would continue to "sound like a laser," not die out. Seeing "No Disk" on HD Set up is another bad sign - the controller of the scsi drive is working but it does not identify the drive or the drive is dead.

If you got it or can get it, use Silverlining and see if it will format from there. But those two signs you stated does not sound promising.