Chosen Solution
If I open the laptop and physically unplug the battery and I start with only the power adaptor, it works. Otherwise, I need to keep the button down for 6 seconds. But! The kernel_task uses 400% CPU and the laptop is very slow. The onboard diagnostic that returns “No issues found. ADP000”. iStat stays that the battery is always using 18.2A (Charger BMON - I think it is SMC register IB0R). The board does not have noticeable water damage. I started measuring voltages on the logic board but I need some help. I would be able to substitute a resistor or a capacitor, maybe even an IC if necessary.
Did you have a liquid spill or sit your system down on a wet surface? While diagnostics is useful it has its limits! If you understand digital electronics we use the term inner-world and outer-world. Diagnostics is mostly limited to inner-world conditions. So analog devices or power being outer-world are just not tested. It also won’t test OS or application issues. ‘kernel_task uses 400% CPU’ tends to be a software level issue. What happens when you boot up under an external bootable drive?
