The ICOM BP-84 is a battery uniquely designed for use in the company's line of handheld marine radios. To get into the battery pack itself is a dangerous but not difficult task that can be done with common tools.
Put on the rubber gloves and eye goggles. Place the BP-84 into a bench vice so one of its side edges is facing up. Close the bench vice jaws.
Saw into the edge, going lengthwise. Go down approximately 1/2 inch into the battery pack housing. Stop and remove from the vice. Place it back into the vice so the bottom edge is facing upward. Saw the bottom edge approximately 1/2 inch down into the housing.
Remove the battery pack and place back into the vice so the remaining long edge, the opposite side from the first saw cut, is facing up. Saw down 1/2 inch into the housing. Remove from the vice.
Insert the flathead screwdriver tip into the sawn slit and gently pry the plastic housing off the battery pack.
Keep in mind that once cracked open, the battery pack can no longer be used in the ICOM radios.
Opening the battery pack is dangerous and should only be done wearing rubber gloves and eye goggles.