Coolers spin and stop intermittently. Computer won't start?

Question

Computers

Hello!
They gave me a working system unit. Before installing it, I decided to clean the dust on the radiator of the processor. The only thing I did was to simply remove the radiator and clean it, put it back as it was.
I start, all the coolers start working for 2-3 seconds, then they stop and after a second they start up again, then they stop again and so on ad infinitum.
There is nothing on the screen. I understand the system does not even start. Help what could be the matter, tk. Are you going to take it in for repair?
Again, the PC worked. I did not touch any insides, except for cleaning the radiator.

Solution of the problem:The issue was solved independently, with hints in the comments. I decided to take it off to check the processor, and I was embarrassed that some socket antennae were uneven, not like the rest. I started to google and it turned out, indeed, this could be the reason that the PC cannot start the system, the protection is triggered. YouTube is full of videos on how to properly fix the antennae of the socket. Armed with a toothpick and a magnifying glass, I straightened this uneven antennae at my own peril and risk.
And lo and behold - the PC started up.

!!! But I want to warn you that this is a very delicate process and there is a chance to break the antennae and then only repair or loss of the motherboard completely. Therefore, if you are afraid, it is better to take it to repair.

Answer 1

Check the connection of the PSU to the motherboard.
Disconnect the power cable from the PSU and the socket, turn off the button (if any) on the PSU
Let stand for 20-30 minutes.
Open a beer, have a smoke.
After the first - plug the cord into the PSU, then into the outlet, click the toggle switch on the PSU (if any)
Wangyu - everything will work

Answer 2

The first thing that comes to mind:
1) The black-yellow processor power wire is not connected
2) The battery died and when the power was turned off, the settings were reset