Hello! Here's my ackward problem: most of the times (8 out of 10), when I plug my laptop using the AC adapter (note: battery is completely dead), the orange light which indicates if the battery is inside gets turned on, but the green light showing power to the main unit (the laptop actually) stays off and I can't turn it on cause the POWER button doesn't do a thing. So again, the orange battery light is lit but the main green one is not, making the laptop not start at all. I've tried taking the battery off, I've even dissambled the whole laptop like 9-10 times already, even replaced and resoldered the small AC jack on the motherboard and still nothing. Worse is that I cannot even find a pattern for my problem, meaning sometimes I am able to start the laptop, but it either shuts down to the above mentioned state OR I can run it for hours, shut it down myself and later when I wanna start it again, there it goes again ... nothing happens
You resoldered the AC jack, but did you check the other end of the problem? Your PSU cable might be going bad - often times the wires inside of them snap after certain amounts of use, and they will only supply power when the cable is given a certain angle. Try fiddling around with it.
Open up the compartment to your hard drive and see if there are loose screws. I could hear one rolling around in there and there was a screw missing that must hold the processor in place. Put the screw back in and was able to restart my computer