A swollen battery case (bulging sides, distortion, visible deformation) means internal pressure has built up from a thermal runaway event or extreme overcharge. Jumping it can rupture the case and spray sulfuric acid.
Same for any battery with visible electrolyte leak, white powdery corrosion crusting the terminals, or a strong rotten-egg sulfur smell. Replace, don't jump.
We replace on the curb at $249 / hour service rate plus battery at retail. Old battery goes with us for proper recycling. Most calls finish inside the 1-hour minimum.