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Question Laptop won't power on and no display after dissassembly and fan cleaning/applying thermal paste

May 19, 2020
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I'm seeking help for my laptop which doesn't turn on. This is after I disassembled it and clean the fan, also re-applying a thermal paste as its temp reaches too high to the point of frequently shutting down.

Upon my first re-assembly, the laptop won't turn on, without display even with external monitor through HDMI. The LEDs seems to work at first boot, the power LED and WIFI LED lights turn on. The fan is also spinning.
However, the second time I tried to power it, only the power LED is left and the fan is no longer spinning.

I tried plugging in my mouse or keyboard to see if it also receives power but with no luck. I also tried removing, alternating, and replacing the RAM modules as I read that it may be the cause, also tred it with my hard drive.Removing the CMOS battery and re-inserting also didn't fix it.

I've read on some forums that it is also possible that electrostatic discharge might have damaged it. Is it possible that I damaged my motherboard while cleaning it? I used a simple brush to remove the dust build up and a hair blower. This is the first time I tried to disassemble a laptop and clean its fans and thermal paste so I have no idea what might have damaged it.
I'm looking into sending it to a technician to troubleshoot it but the cost of service in my country is expensive, plus I can't really go out due to the quarantine.

edit: I am pretty sure that I did not leave any ribbon connectors unplugged as the only thing I unplugged was the keyboard connector in addition to the heatsink fan. I also did not remove my processor as I am aware of the delicacy of the pins.

My Laptop specs:
Toshiba Satellite C850, i7-3630QM with AMD 7610M, 6GB RAM, 1TB HDD
 
Last edited:

lga1156_ftw

Prominent
Feb 25, 2020
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disassembly until 5.00minute on this video :
View: https://www.youtube.com/watch?v=vwmpb2KNuGg

Remove the CMOS coin battery, when cmos battery is removed you do not have to press power button for powering on. Connect external monitor and then plugin power cable it should boot right away, this will remove the keyboard and the power button / front panel as the problem. If you get picture without front panel then issue lies there.

Everytime when you test with power cable make sure nothing is touching the motherboard from the loose connectors etc, and plug powr off after every test.

If it doesnt work plug off power cable again and take off heatsink, after that use screwdriver to open the CPU socket, there is a small clip you can see on 1,25min in this video:
View: https://www.youtube.com/watch?v=Nb_RSEf-br0


Take out the cpu and insert it back carefully, when its in place use the screw to tighten it back, after that insert heatsink again (slowly tighten screws from opposite directions , not too much force) and test booting with power cable (+ external monitor)

Look all connectors very carefully and reinsert them if necresssary if you used brush to wipe the whole motherboard there might be loose connector. LCD cable is near the processor and heatsink just north from it, you can try to remove it then test with power cable + external monitor if issue is shorted LCD cable ( you somehow broke it while cleaning if you get pic on external)
 
Reactions: brxbrxbrx
May 19, 2020
4
0
10
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Hey
disassembly until 5.00minute on this video :
View: https://www.youtube.com/watch?v=vwmpb2KNuGg

Remove the CMOS coin battery, when cmos battery is removed you do not have to press power button for powering on. Connect external monitor and then plugin power cable it should boot right away, this will remove the keyboard and the power button / front panel as the problem. If you get picture without front panel then issue lies there.

Everytime when you test with power cable make sure nothing is touching the motherboard from the loose connectors etc, and plug powr off after every test.

If it doesnt work plug off power cable again and take off heatsink, after that use screwdriver to open the CPU socket, there is a small clip you can see on 1,25min in this video:
View: https://www.youtube.com/watch?v=Nb_RSEf-br0


Take out the cpu and insert it back carefully, when its in place use the screw to tighten it back, after that insert heatsink again (slowly tighten screws from opposite directions , not too much force) and test booting with power cable (+ external monitor)

Look all connectors very carefully and reinsert them if necresssary if you used brush to wipe the whole motherboard there might be loose connector. LCD cable is near the processor and heatsink just north from it, you can try to remove it then test with power cable + external monitor if issue is shorted LCD cable ( you somehow broke it while cleaning if you get pic on external)
I got it to boot into bios now! Removing the CMOS battery then plugging in worked. Now I re-inserted it back and it boots fine now. Thanks!
 
May 19, 2020
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I do have another question though, about updating my bios. Currently my installed bios version is 6.10. I looked for updated drivers in toshiba/dynabook drivers site and found that there is 6.80 bios version available. Upon launching the application, it says 'insert battery' then quits suddenly. My battery is long dead now as it is already 7 years since I bought my laptop, I've been using it with the AC since then. How can I update my bios to latest version without inserting battery? Or is it necessary to update my bios to the latest version or I'll just leave it at the old "seems fine and working" bios version?
 

lga1156_ftw

Prominent
Feb 25, 2020
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Just leave it on the old version no need to risk it again, there is a way to bypass the "battery check" but dont do it.
So it boots fine now with keyboard / front panel connected? Probably a loose connector caused a short or similar issue. If you start getting "wrong date reset cmos" message on startup that is a sign that cmos battery has gone bad ( too little voltage) , its easily fixed by replacing it but i dont think thats the case, usually takes 10 years or more for it to go bad.

If you still get issues later on replace the cmos battery.

You can mark this tread as solved, select best answer.
 

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