Welcome to the forum
I'm afraid you won't be able to change your SOSW-833S into an ND-6500A :disagree:
They are made by completely different manufacturers, with completely different chipsets.
Either you will have to stick with your LiteOn drive, or replace the drive with another ND-6500A.
EDIT: You may try ISO Buster or ISO Puzzle, to see if they will help you retrieve the data on your DVDs.