How do you get swollen corroded battery out of camera flash

[sterretje]

Things I would try

• Tweezers.
• Drill bit. Pre-drill a small hole in the battery; next use a bigger drill bit and hope it hooks when you try to 'drill' it with your han and that way turns the battery so it comes loose.
• Drill bit and additional tools. Basically drill the inners out of the battery till you can manipulate the battery casing; long nose pliers to grab the battery casing and carefully try to twist / pull it out.

Note that if it's severely coroded, it might be 'glued' to the contacts in the battery compartment and pulling the battery out might damage those contacts.

[AquaDome]

I have had luck with freezing overnight, then thawing a device that had swollen batteries in it. After thawing for an hour, I banged it against the padded arm of the sofa a few times and the batteries came right out.
If there is significant leakage and corrosion, they might be cemented in there for good.