Defrosted shrimp, parts are opaque white? Is the shrimp good? Freezer burnt maybe?

Sounds freezer burnt. Still ok to eat as long as it's within expiry date and smells good. The white parts may be tough but still eatable.

It may have thawed slightly and then refroze in your freezer. It's still good to eat if you cooked it properly. This happens often in the summer if it took a little while to get the shrimp into your freezer from the supermarket.

See shrimp in middle for examples of the opaque white parts. Sorry - might be a dumb question but I don't cook a lot of shrimp!