Laptop won't post after replacing daughter/mother board ribbon cable

[RushIsRight97]

Last week,
I purchased a used Samsung notebook 9 Pro ( np940z5l-x03us ). It worked perfectly. I then shut it down and stored it dormant.

Yesterday,
I took it out, and opened the back panel to check if the SSD was NVME or Sata ( I was going to buy more storage over black Friday / Cyber monday).
Since the SSD lies under a “Main/Sub motherboard connector” ribbon, I removed the ribbon.

Problem Event + Symptoms:
Whenever I checked the ssd and then reconnected the ribbon, I noticed the main motherboard fans spin up for about 0.5 sec and then stop.
Now, the laptop is totally unresponsive. Only the battery indicator LED works, if the laptop is plugged in (green light for full charge and red light for charging battery).

I have tried:

• no battery booting (only AC power booting),
• remove battery, drain power via Power Button, replace battery 20 min later, try to boot

Image:
https://www.mobiletechreview.com/notebooks/image/samsung_notebook9_pro_guts.jpg

Any advice on how to proceed?
Many thanks,

[Levent]

those ribbon cables sometimes can be tricky to seat back in. Are you certain that its making connection on both ends? Also have you removed the SSD? I had Asus laptops that wouldnt boot unless DVD drive was plugged in.

[RushIsRight97]

_

Edited November 29, 2019 by RushIsRight97

[RushIsRight97]

1 hour ago, Levent said:

those ribbon cables sometimes can be tricky to seat back in. Are you certain that its making connection on both ends? Also have you removed the SSD? I had Asus laptops that wouldnt boot unless DVD drive was plugged in.

haha!... sort of.

 

I plugged in the ribbon in forwards, but I chose to try it backwards just in case.

 

So, I unplugged the PC and swapped the ribbon around.

The pc booted to the login menu automatically while I was switching the cable around. At the time, the ribbon was completely connected to the duaghter-side and partially connected to the mother-side. (as shown in the image, the yellow-squared foam pad fits nicely between a gap if placed right-side up, but it pushes the ribbon connector up if inserted backwards.)

 

Since the laptop was running with the daughter disconnected, I chose to shut down the pc and connect the ribbon right side up. Now its not booting, but it does now display a charging status screen if plugged in.

 

Conclusion:

Maybe a bad ribbon or daughter-board (power-button)?