First, You should know that a leaking battery does not always mean any electronics the battery fluid has touched is ruined. Quite often, depending on the severity of the leak, most battery fluid spills can be quickly and easily remedied with a few common household items, and maybe a trip to the electronics or hardware store.
Most alkaline batteries store their electrical charge in a chemical device, the battery cartridge.consumer electronics (AAA, AA, C, D, AND 9VOLT) batteries are composed of alkaline electrolyte of potassium hydroxide and zinc powder and a chemical insulator between the two nodes. Over time, alkaline batteries are prone to leaking potassium hydroxide, a caustic agent that can cause respiratory, eye and skin irritation. When a battery leaks usually the cathode or + end with the raised button will leak the caustic potassium hydroxide fluid into the battery case of your microphone. The battery fluid can cause a lack of conductivity on the battery terminals of your microphone and sometimes the circuitry also.
SOLUTION: First collect these items, Rubber gloves. The latex tight fitting type for protection from the caustic potassium hydroxide. Cotton swabs. You can use the small double ended cardboard type found in any drugstore or pharmacy. A good electronics store will have long wood handled cleaning swabs (usually single-ended or one swab per wooden stick) if you need more reach inside to clean the compartment.. A small cup or can. Warm water. Baking soda. Paper towels or napkins.
very fine sandpaper (400 grit or higher) or emery cloth. dish soap. cotton swabs. an old toothbrush and clean , lint free rags. a blow dryer Open and disassemble the microphone as much as possible without disconnecting any soldered wires. The idea here is to access ALL the surfaces of the mic so they can be cleaned of the caustic potassium hydroxide. Make a nice solution of about one cup of warm water with one drop of dish soap add one tablespoon of baking soda. Stir well. With your gloves on, use the baking soda solution to clean the terminals and surrounding areas where the fluid has spilled. Use swabs, cotton and towels with the solution to clean the terminals, the surrounding areas and any circuit boards of the spilled fluid. Do this as soon as you discover the problem, otherwise the powerful corrosive effects of the fluid will cause iron and zinc oxides (rust) to form and these will require a more aggressive approach, namely abrasives. If there are any rust like deposits left after cleaning with the baking soda wash use the blow dryer to completely dry everything. Sanding should be kept to a minimum but is sometimes "a necessary evil". The idea is to clean the nickel chrome battery terminals and NOT remove their nickel chrome from the spring-steel battery holder/terminals. You want to clean the terminals, not remove so much material that the conductive plating is also removed or the battery doesn't fit because the gap filled by the battery is enlarged. You just want to clean the chrome surface of the battery terminals of your device. Make sure the unit is clean and completely dry before installing new batteries. re-assemble your device if necessary, load new batteries and power up!
This is a common repair for any unit which has been stored with old batteries, or if exposed to prolonged heat or humidity. Store all battery powered devices, especially transmitters, or remote controls in a cool, dry, place, removing battteries if stored over 6 weeks.
If this solution provides no repair, it would be reccommended to seek the Manufacturer's authorized repair center nearest you, or just replace the unit.