Hmm heres the problem. When you try to replace CD-rom drives in a Saturn you can get problems with incompatability. I have 3 different types of Saturns. Old US august 1996, newer US October 1996 and a see through blue Japanese skeletal made in 1997. The cd-drives were not interchangable. You got two models that have a crystal on the cd board and two models without the crystal on the cd board.
Of course I guess you could remove just the black casing part from the boards and maybe switch out just those parts. I say just get another Saturn, I bought a US one for $20 console only, then just you could just switch the casings and never know a difference (except when you boot up and also region code will be different, but you can just use a Pro Action Replay 4in1). There is an e-bay seller that sells defective Saturns for $5 but I bet all of them are defective because of the motor or lenses.
***Try this, open system, check the ribbon cable if it is inserted tight. Also if you happen to have a mod chip inside it, then I bet its fried (It's somewhat common). Take out the mod-chip and reconnect the ribbon to system.