It sounds like the battery corroded in place.
First, you could try a small flat screwdriver. Try to get the blade between the battery and the housing wall. You might be able to get the battery to wiggle enough to break it loose. You could even attempt to twist the battery from this position
Second, you could try a long wood screw (or deck screw). Screw it into the top of the stuck battery and use it to twist, wiggle, pull on the stuck battery.
Third, you could use a baking soda in water solution (or vinegar). Pour the solution into the tube and shake with the opening covered. Hopefully it will dissolve the corrosion and free the battery.
Peace,
dave