Fabreze is worthless- there is a product called fizzion (made for pet stains/odors) that is nothing short of magical. I haven’t tried it on a camera case but it would be worth a shot.
I agree about Fabreze.
We've tested Fizzion because we have a cat that won't stop urinating on the carpet (we're trying different remedies). It's good at removing various stains (non-pet related ones as well) - even very old, worn-in stains. It's not the best at removing the urine odor.
That said, cat urine odor is far worse than a mildew smell, so it may be worth a try.
If you try it, test on small areas first. It has been color-safe on our carpets, but you'll want to be careful. Also, don't mist the area, put on enough that it can soak in a bit (but don't saturate like you would a urine-spot).