Check any disposable batteries left inside items.

Disclaimer: Zero liability, past, present and future.
I'm not picking on any brand.
It just a kind reminder to occasionally check or remove any forgotten batteries left inside household items and photographic equipment.
My wireless meat thermometer batteries died.
I was very surprised the cleanup wasn't any worse.
I'm very happy it was not in any flash unit.
Some battery compartments have the batteries lying flat.
Some vertical battery compartments are deep and nearly impossible to clean if a battery leaks.
I'm not promoting any brand. Just sharing what I personally use.
I try to purchase energizer batteries for anything expensive. No leak guarantee.

Yeah, I'll say..........I bought a used 580EXII on Ebay and all four had leaked all over the battery compartment. Seller didn't bother to check or disclose. You know how much of a mess 4 of these can make?

Good ending to the story though. After hammering them out with a rubber mallet and some extensive cleaning with Vinegar I now have a fully functional and as new 580EXII for a real bargain.

It is a good practice to 'break the circuit' simply by putting a piece of tape on an end of one cell. Realize that switches now required a CONSTANT presence of Voltage in order to recognize when you press the Power button. If you interrupt the flow of electricity, the batteries are less likely to be drained to the point they become exhausted and leak.
I have never seen leakage when tape breaks the circuit! Admittedly it is a bit of a nuisance to have to pull off the tape before being able to turn it on, but there are many devices that we want to be able to use, but very infrequently...like a flashlight in case of a power failure, and pulling off a bit of tape is not that inconvenient when it is finally needed.
Remember...new products often come in their package with installed batteries, and you pull the tape to use it...have you even gotten a new product with corrorded batteries?!

lastly, look in a grocery/hardware store in housewares for a cleanser called Barkeeper's Friend. If you make a paste using the power and a small bit of water, and put it on a Q-Tip, it will dissove corrosion on the contacts in the battery holderl, and then use another Q-Tip moistened with water to remove the stuff off the terminals and let it dry before use; I have salvaged a number of items in which battery corrosion had occurred!

Thanks. I have a can of bar keepers under the kitchen sink. Also noticed the thin plastic on new product contact points.