Error 400 is a general read (transcoding) error...doesn't tell us us much in terms of specifics.
Try cleaning the disc first...just windex, isopropyl alcohol etc. and a decent microfiber cloth.
Since you can see a lot of surface scratches, probably go to step #2.
Brasso polish and the same type of microfiber cloth.
Brasso works great as long as it's not gouged...
