I suggest taking some berries out and looking at them after they thaw. If they were in a regular non-frost free freezer they will be in better condition than a frost-free freezer, as they will not have went through the constant partial thawing that takes place in frost-free freezers to keep them frost-free. If they were in a frost-free freezer, I would guess they are no good and probably need to go to the
compost. However, in a regular freezer, they might have made it if they were in a well sealed container. If you thaw some, and it looks, smells, and tastes great, then they are probably good to go. If you do decide to make syrup, I would suggest only making
enough syrup to get you through until this next fall and then collect new ones.