How do I remove the AA battteries

The cells swell, making them difficult to remove. If you can't get purchase on them with needle nose pliers, you'll have to drill a hole into the bottom and remove with a screw or hook.

When you clean the contacts, don't use baking soda, as is often suggested. The corrosion from the cells is alkaline, not acidic. vinegar on a Qtip will neutralize it. Then get the vinegar out. Swab it with water or isopropyl alcohol. Don't slop it in, you don't want any of this running into the camera.

Alkaline cells should never be used in these cameras. They are inferior in every way, but especially because they always leak, often destroying the equipment. Alkaline cells have very few legitimate uses.