If your tri-wing screws are seized up as mine were, you can nibble away the plastic around the screw mounts on the battery with long nose pliers and a flat head driver enough to extract the battery. I then unscrewed them with the pliers. Have replaced tri screws with Philips.
My tri-wing screws were black, 2mm and totally seized up. I had to break the plastic around the screw holes in the battery, remove it and then un screw them with long nose pliers. Needless to say they are now replaced with Philips screws.