Solved! Lenovo G400s stuck at black screen but power,fan&screen led light on, also cpu and gpu produce some heat

[Ferdy89]

Hi, im using lenovo g400s and this is my second time reapply thermal paste and cleaning the fan. The first time was fine but this one causing a problem which my screen stays black when turn on and stays like that forever no restart, etc, need to hold power button for a long time in order to turn off the pc.

I grounded myself by sitting on the floor and remove the battery before i clean up the fan and reapply thermal paste. I was using magnetic screw driver i didnt know if it will cause trouble or not, but i didnt smell any burn.

When i turn on my laptop the fan turn on and gradually become faster but not very fast like when i was rendering or playing games. Gpu and cpu showing a little bit of heat and i can hear my hdd sound. The led light indicator on the top of the screen beside the camera turn on but screen stays black so i decided to plug in the charger and i heard bepping sound once which never happen before everytime i plug in charger. But it does nothing so in the end i turn off the laptop by holding the power button for around 10s. After that i press the bios button beside my power button and it usually bring me to bios setting but this time does nothing. Also the led indicator beside the camera normally turn on when booting up but eventualy turn off when windows login screen appear and this time it keeps turn on forever while screen staying black forever so i thought this is the problem with the bios or the windows so it cant boot up to windows.

So i try to reset bios by unplug the connector of cmos battery to the motherboard and waiting for around 20 minutes and plug in back the connector then press the bios button and it does nothing and then i press the power button and screens stays black. I remove the laptop battery before unplug the cmos battery connector.

I really dont know what happen to my laptop the second time i cleaned it and reapply thermal paste. any suggestion or solution and what is the problem? Anyting that can help appreciated. Thank you.

here is some image:
Led light indicator & blank screen forever
https://ibb.co/y0G87Z6
My motherboard
https://ibb.co/ZVb0RBq

IMG-20210116-215453 hosted at ImgBB

Image IMG-20210116-215453 hosted in ImgBB

ibb.co

 

[AlHuneke]

You had the right idea, but sitting on the floor is not grounding yourself (unless that floor is metal and grounded). If it was carpet, that's really bad. Wood or vinyl not as bad. You could have misconnected something, messed up a connector or zapped a part with static (there would not be any burning or a detectable spark). However, I suspect something is zapped.

I've never been a fan of cleaning and repasting. I read a lot of posts just like yours that something bad happened after repasting. At most, you should only need to repaste once if a good paste is used. The screws need to be retightened properly like you were reinstalling a head on an engine. Never use a brush or vacuum to clean the fans and air passages. Use a can of compressed air designed for this purpose.

Using a magnetic screwdriver won't hurt anything. I would keep it away from the drive if you have a hard drive. As SSD is not an issue.

 

[Ferdy89]

You had the right idea, but sitting on the floor is not grounding yourself (unless that floor is metal and grounded). If it was carpet, that's really bad. Wood or vinyl not as bad. You could have misconnected something, messed up a connector or zapped a part with static (there would not be any burning or a detectable spark). However, I suspect something is zapped.

I've never been a fan of cleaning and repasting. I read a lot of posts just like yours that something bad happened after repasting. At most, you should only need to repaste once if a good paste is used. The screws need to be retightened properly like you were reinstalling a head on an engine. Never use a brush or vacuum to clean the fans and air passages. Use a can of compressed air designed for this purpose.

Using a magnetic screwdriver won't hurt anything. I would keep it away from the drive if you have a hard drive. As SSD is not an issue.

My floor is made from ceramic and im on the second floor lol not the first floor, is that count as grounded?

Do i could touch the mother board component using magnetic screwdriver, maybe accidentaly touch it with magnetic screwdriver?

Is it better to touch your screwdriver first to the ground before using it? Or is it unecessary

 

[AlHuneke]

A ceramic tile floor is not grounded. You can still build up a static charge on your body. Here's what I would do in your situation:

• Try not to move around much rubbing against the floor.
• Open the computer and look for large metal object. These are usually things like covers. Touch that with your finger to equalize the charge between you and the computer.
• If you remove parts. get a sheet of aluminum foil, touch it while touching the metal in the computer and lay any parts (like RAM) on the foil.

Touching parts with the screwdriver might cause a spark (too small for you to see) bit enough to cause damage. Keeping your body at the same voltage as the computer by touching metal in the computer while working will prevent this.

I work on a special grounded mat on my workbench and wear a wrist strap connected to ground (the ground pin on an AC receptacle.