Playstation 4 PRO CUH-7116B BLOD

Hello everyone, the situation is as follows.
I bought a PS4 pro as a non-working one, or for spare parts to try to repair it. At the very beginning, it turned on for 3 seconds, there was a blue flash and it turned off.
Later, I put 3 washers under the APU/CPU mount, and after that it stopped shutting down. But the blue light doesn’t go away, it just stays on endlessly and doesn’t turn to white until I turn off the console itself.
I can’t switch to safe mode, because when I hold down the power button, it turns off after a while, but does not switch to safe mode. And the problem is definitely not in the power supply, because the console works, and not in the hard disk, because I checked it on a PC and it works.
Also, please tell me if the light should turn to white if the console is not connected to a monitor, and if the hard disk needs to be reconfigured somehow if it was once used on a laptop.

If adding washers changed the behavior, it’s almost certainly a APU issue. Try booting with the HDD removed for good measure (the light should turn white and it should show an error screen), but def sounds like APU (or maybe RAM?) to me.

I have try to boot without the HDD, but nothing changed(

You could look into reading codes via UART, but APU is the likely culprit IMHO.