Help, took apart Lenovo P53 Workstation to redo thermal paste and now it won’t turn back on

[HimeBun]

I’ve taken it apart and put it back together about three times now just to check and see if every connection is made complete, and I still haven’t been able to get it to turn on, when I press the power button the lights turn on and the fan starts spinning before abruptly turning back off, while the light on the power button remains on, I need help figuring out what this problem is

 

[Theinsanegamer]

Have you already done the power drain reset listed on lenovos website?

Troubleshooting No Power Issues - Lenovo Support US

pcsupport.lenovo.com