Battery Leakage and Corrosion
Here is an incident where a customer turns in the calculator. He claimed that he had just change battery for about 2 weeks. Here is a picture of the leak and mild corrosion could be seen on the battery lead.
What happens is the "cheap" battery leaks out an alkaline: Potassium Hydroxide. This is a corrosive base, much like lye. The way to neutralize the leakage, after removing the battery, is to wash the affected area with a solution containing a 50 / 50 mixture of (white) vinegar and pure water. Scrub carefully with a good toothbrush, and then rinse with pure water. Cotton or paper towel wipe the inside of the battery compartment. Use a COOL blowing hair dryer to eliminate all moisture from the compartment. Luckily, it did not affect the calculator board. After the clean up and replacing a brand new set of battery, the calculator is able to power up.
Alkaline battery leakage is extremely caustic and contact with bare skin should be avoided. In the event that battery leakage comes in contact with your skin, flush the area for 5 minutes with copious amounts of water.
Remember to use good quality "branded" battery for your calculator.