Question Pc unable to boot after replacing thermal paste

[Hye Xenforo]

Hello. So i decided to replace my thermal paste and clean the PC as i did everything corresponding with the parts and reassembled again the pc doesn't like to boot to BIOS. All fans works though gpu cpu case fans , PSU... And no beeps. I did reaset all cables, cpu, ram, gpu even cmos still no luck. What could have gone wrong? 😔
Okay so after a bit of playing, seems the pc before loading the BIOS it does itself shutdown, and after 2 seconds turn on again itself. What could be the culprit

 

[Misgar]

If you have a modular PSU, did you unplug the power cables at the PSU end or from the motherboard, GPU and SATA drives? Some power cables can fit in the wrong sockets on the PSU, with potentially catastrophic results.

You must have changed something when you reassembled the system. Check again, even more carefully.