Replacing battery on a Runner 2 (I think similar to Runner 3) does not require removal of vibrator. There are 6 screws. The battery can be removed by gently wiggling it loose with a thin blade. The battery has a little adhesive, so it won’t come loose by itself. Start lifting it on the opposite side from the ribbon connector (which runs from screen side to back plate). The last part of removing the battery requires wiggling the battery from left-to-right (looking into the watch with the ribbon connector away from you), because there is no room left for up-down movement. Check the shape and wire colouring of the battery connector at this point! Once loose remove the battery connector by using a small screwdriver to lift up the connector (don’t need to pull the wires or anything). It just pops out. The new battery can be connected by inserting the connector down into its socket. Push down gently. Make sure you insert it with the correct side down (the little openings on the connector should go down). HTH