Shut off during startup
I've a MBP 2009. With time, I have more and more difficulties to start the computer. When the computer is "cold" (no boot for some hours) and you press the power button, it tries to start (2-3secs), and then shut off. So I restart, again, again and again. With tries, it shut off later. Finally, I'm able to reach login screen. Then the computer is stable and I've no more shut off. I can keep it running during 24 hours without issues.
It's like the issue is happening when the computer is not "hot" or needs energy.
Here is the result :
It looks like the battery is fine ?
Thanks @mayer. I replaced the battery with a new "genuine" one. Unfortunately, it doesn't solve the issue. It is still exactly the same. I'm also surprised that even with a new battery, if I unplug the magsafe, the computer shutdowns 2 or 3 seconds after that.
I'm now wondering if it's not an IC issue related to power on the logic board. Maybe you have some more hints ?