vinegar or electrolysis

depends on how bad it is. I know white vinegar should be safe on plastic, but I am fairly certain its not safe for foam or rubber (at least I never let it touch those for extended periods when I use it)
If you just have a little surface rust around the hinges, electrolysis would be overkill. Thats really a process better meant for larger parts with nooks and crannies that aren't easy to get to in my opinion.
I have also just put a little 3-in-1 oil on hinges and hard to move garden tools and cycle it open and closed and you will see the hinge work the rust out on its own, wipe it off with a clean rag and then repeat the process. It won't change much visually, but should be able to function normally after a couple of treatments like that.
If you're still not sure, don't be afraid to send a picture of it so we can give more ideas