Oh, boy. James, given that you had a "swollen battery," it sounds not good! Swollen power sources are often caused by excessive current drain (overheating), which are often a result of a "short circuit," which often remain until the component causing the "short" has heated to the point of decomposition - which results in a new problem, an "open circuit." At that point, repair becomes expensive and not worthwhile. Unfortunately, it requires some skills to determine this. How're you voltmeter / electronic troubleshooting skills? You mentioned you had changed the battery; did you happen to scan the exposed circuitry to see if you could spot any other swollen or blackened components or fried conductors / circuit tracks? As Lord Vader asked, can you tell if the fans start running? Can you check the voltages on any of the components - to see if any exists? This sounds like something more than a mere software problem...