Greetings mac rumours, I have a MBP that will only boot when the Magsafe cable is attached AND the battery is removed or at less than 100% - the power button is completely unresponsive. The problem started with a failing battery that had swelled to the point of making the click pad unusable. Towards the end of the life of this battery the MBP would fail to hibernate if the battery ran out, and upon being rebooted the computer would have reset it's clock to December 2001 and have forgotten recent additions to passes in the keychain. This battery eventually failed (I presume) - leading to a computer that was completely unresponsive to the power button. I removed the battery, which led to the first instance of the computer only booting when connected to a power source. If the computer (now without battery) was connected to a power source, (which in turn leads it to boot up), then turned off again, the only way to reboot the computer was to physically disconnect and reconnect the Magsafe adapter. I ordered a replacement battery and installed it, the problem of booting only by connection to power persisted. A novel twist was that when the battery is fully charged and displaying a green light the MPB will not boot at all when the magsafe is connected - the battery must be removed or at below 100% charge. During normal operation (such as now) the power button remains completely unresponsive. A short press will not bring up the option to shutdown / sleep my computer and a long press will not perform a hard shut down, as per normal operation. I've attempted to reset the SMC following Apple's instructions several times, to no effect, with the battery removed and with a working battery installed. Perhaps of note is that the times I've tried the SMC reset I've never experienced the LED on the Magsafe changing states or temporarily turning off. Also to be noted is that this is the first time I've ever opened the back of my computer. I'm very inclined to repair as much myself, but if we're going into circuit boards it might be best to pay someone with experience. Really stumped as to what's going on here - any takers? Cheers in advance, Will.