I have found that different techniques are needed for different parts of the job. The outermost two batteries on both sides can be removed by softening the adhesive as shown with the fluid. The batteries are in a shallow dish so there is less chance of the fluid running everywhere. Just apply sparingly. As Christopher Girke suggested, the middle two are best removed by applying the solvent to the edge of the card. Multiple applications are necessary but this avoids the fluid getting where it should not go. Also it is easier to push in from the sides, not the front as shown in the photo to avoid a lip on the underside of the trackpad.