Yep, booted into OS 9 and the drive didn't do much except spin and then stop. I also tried inserting a disk before booting and nothing much happened. You would think it would spit the disk out if it isn't bootable.

This is not the original 233 MHz iMac logic board, though, this is the 333 MHz one - maybe that makes a difference? I noticed that the 233 one has an actual port mounted at J4 for the IrDA but this one doesn't, only the traces are there.