Old batteries can fry the charger, charging circuit or motherboard. I don't know why folk think old batteries are worth frying the entire laptop but you see it all the time.
Now test without the battery. If it works, well, it's better than a fried laptop.
I've had this issue on monday where I tried to turn on my laptop, the power light came on but for 10-20sec the light goes out. Usually when I press the power button, windows will start up but it didn't. I tried swapping on the cable for the battery, It turn on. I shut down and remove the batt for the power cable. Laptop turn on normally.
Just now, I tried turning the laptop, same thing happen but this time I tried to power up the laptop with cable and battery nothing happen. for a hour or so I powering up a few times and nothing happen, only moment ago I manage to power up the laptop. You or anyone experience this before?
The condition of my laptop: it's about 5 years old, I got my harddisk change early this year.