HP Z440 Motherboard won't turn on

[RBBG]

Hello,

In short: Dissambled HP Z440 to see which components could be reused in different (standard PC), removed heatsink from the m2, SSD inside the custom HP PCIe component. When I put it back in the desktop it wouldn't start. PSU still works. Motherboard still gets the 5V. Shorting it doesn't work. Am I screwed?

Longer:

Want to upgrade my desktop so was looking at which components could be reused (most is custom so not much). Already upgraded the workstation to a RTX 3070 last year. Was taking pictures of all the components and disassembled the whole system. Also disassembled the custom PCIe component which is presumeably for start-up? To see wheter I could upgrade the SSD or just use that SSD in a new system. Once I assembled the system again. Plugged the 2 pin connector with the brass component facing towards me in the connector. Seemed to work once (when I removed it to get a better look at a different component. Second time; machine doesn't turn on anymore.

Tried the paperclip trick on the PSU, seems to work, PSU still turns on. Tried to remove the front-end cable and short the power pinout following this post: https://h30434.www3.hp.com/t5/Desktops-Archive-Read-Only/Front-panel-connector-pinout/td-p/5540808. Also doesn't work. The Lan-gate still lights up when I plug the power in, so the board should recieve the 5V from the PSU. Can't see any damage on the motherboard but might be fried? Anyone addition tips to get the motherboard to power-up? Or did I just screw up?

[RBBG]

http://h10032.www1.hp.com/ctg/Manual/c04823811.pdf 

Found the user manual, seems the board just needs to be replaced as stated on page 82-83.