My PS4 won’t turn on after I opened it up to fix the loud fan

My PlayStation 4 was very loud to the point where it got annoying hearing what sounded like a jet. I looked up some videos online to guide my way through to fix this problem. I did everything the same way that the people did it when fixing it. When I got done putting it all back together, I plugged it back it and when I tried powering it back up the PlayStation didn’t turn on. Please help!