The error you are getting is related to the optical drive. I would suggest you to reseat the optical drive once, before replacing it. For Service Manual, please refer to the link: http://bit.ly/Tm9a4F.
Hope this helps. Please feel free to reply for any further assistance.
Thanks & Regards Amogh G #iworkfordell To know more about Dell Product Support, Drivers & Downloads, Order & Dispatch status -> choose your region USA; India. For helpful Dell Support Videos, you may click Here.