Solved! Replaced laptop daughter/motherboard ribbon, now won't power on.

[Layton99]

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 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,

 

[Greg Chalik]

Just a hunch, but you may have reconnected the ribbon backwards.

 

[Layton99]

Just a hunch, but you may have reconnected the ribbon backwards.

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.



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)?

 

[Greg Chalik]

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.



I just looked at the video of someone upgrading the SSD and the ribbon cable [rainbow] I see is connected to the battery? This may explain why the fans activated on disconnect. Did you earth yourself before touching anything inside the notebook? The ribbon cable may have been affected by static electricity, IF that is all you touched.



Conclusion:

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

Maybe you transmitted static electricity while hadling? If the machine was working well before your removing the ribbon cable, it isn't just decided to spite you and stop working. What do you mean "partially connected"? The 'mother-side' is the motherboard. What does the daughterboard do?

 

[hang-the-9]

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.



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)?

The system turned on while you were working on it? You did not unplug the battery? Sounds like either you fried something or something is not connected properly. Nothing really here to check on outside of having the system there and look at it. It's a guess as to what may have happened when you had it open.