Question Windows 10 Shutdown but my pc led still on

[YesMyNameNewbie]

I am confuse right now,
This is my first time handling PC like this.
Short Story, I got an old pc from my uncle and i want to do some minor upgrade.
the pc is Lenovo ThinkCentre with i3 intel cpu gen 2

So after upgrade the ram, add new ssd and hdd, and install windows 10.

After I shutdown the pc, the led still on.
I think it's been "On" like an hour, I know it later after I surprised that the led still on.
When I try to boot up like a normal (push the power button), it Can't boot up.
I have to hold the power button until the led shut down, and re push the power button.

I'm certain that the windows is shut down because, it's like a normal shut down (The monitor turning off).
But literary I'm Surprised that the led still "On" after an hour.

I have been doing something like
1. Disable Fast Boot on Windows Power Setting
2. Disable all related automatically power turning on at the BIOS.

And the problem still not solved
Can anyone help me ?

I'm sorry if my English so bad, I'm still learning.