I left my Dell Inspiron 1420 on overnight and when I checked it the next morning it was completely dead. It was operating on AC power, without the battery in. The AC adapter light was out when it was attached to the laptop. When I disconnected the adapter from the laptop and switched on the mains, the light came on, and it like it could function normally. However, once I connect it to the laptop, the adapter light goes out. The laptop cannot power on on battery alone, or with battery and AC power connected either. The battery does not charge either. The laptop gives no response (no lights no sound) when the power button is pushed. Even without any peripherals attached, the laptop cannot power on at all. I had not installed any new hardware devices or software, except for the fact that I do leave my laptop on overnight quite often. I do not think it could be due to overheating as the laptop temperature has never gone above 'uncomfortable to touch' levels of heat, and I always use a notebook cooler. What could have caused this problem?