PC boots up for 3 seconds and shuts off after mainboard disassemble

Posted by Apart_Beginning6826@reddit | buildapc | View on Reddit | 10 comments

I wanted to change my cooler so I needed a new backplate. I had to remove the motherboard and build it again. After I did that my PC was not booting up, but rather it starts to boot up for 3 seconds and it shuts itself off. The power button does not seem to work. The thing is one time i did get it to boot up and I even played games, did benchmarks etc. After that I had the same problem again. I literally tried everything, from building everything again, to removing the battery of the mainboard and changing the cpu thermalpaste. Nothing seems to work. If it helps in any way I have a Lenovo Ideacenter T540-15AMA G Desktop.