iMac24"(A2438) cannot boot smoothly

I have an iMac 24" (A2438). If I unplug the power supply for too long, there will be no response when pressing the power button. If I unplug the power supply again and then plug it back in immediately, it will turn on.

If I do not unplug the power supply, this phenomenon will not occur and the computer will boot normally.

I have tried replacing the power supply, button battery (CR2016), and power supply board, but there is still no improvement.

Ask if there are any other parts that are faulty?

Thanks