Solved! Laptop does not boot after CMOS BIOS battery replacement.

[acanicio]

Dear all,
My name is Axel.

I have a CLEVO W870cu laptop since 2011.
My laptop's battery has been dead for quite a while, so I run the laptop only on mains.

For quite some time I've had to set the correct date and time and enter setup at each reboot, so I decided to change the BIOS battery.
Unlike regular laptops, the battery is a simple CR2032 lithium battery that seats in a battery holder.

After I changed the battery and reconnected and double checked everything, the laptop won't boot anymore.
On pressing the power button this is what happens :

T+0 : The GPU fan starts spinning normally, power light lights green), bluetooth light is on. No POST. Screen stays black. The CPU Fan does not spin.

T+30s : The GPU fan goes to full speed, power light and bluetooth stay on, but caps lock, num lock and scroll lock start blinking a t about 1 Hz .

T+75s : Laptop shuts down (after 48 blinks of the lock leds.

No beeps.

This is what I tried :
I removed all integrated peripherals (HDD, DVD, only left only one 4Gb ram stick.
-> Same issue.
Disconnected Bluetooth and wifi modules
-> Same issue.
Swapped both CPU and GPU fans
-> Same issue.
Changed the ram stick
-> Same issue
Removed all ram sticks
-> Same issue
Re-seating new battery
-> Same issue
Re-seating GPU MXM card and CPU (replacing thermal paste) and heat sinks.
-> Same issue
Removed GPU.
-> Same Issue

Removed CPU
-> Nothing happens, the laptop shuts down after 3 seconds.
This means that the CPU is not impacted and seems to be doing something during the first 30 seconds of the startup process.

Does anybody know the error codes or signs for this specific brand or model ?

Does anybody have any hint on what could go have gone wrong, apart from incorrectly reconnected connectors ?

Thank you
Best regards

 

[AlHuneke]

Unfortunately, I see this type of email a lot. It's not your fault but the fault of all the clueless people on you tube that post how-too videos. Any time you work on a laptop (unless you are very experienced) the first step is to get ahold of the service manual. This is easy for some models and impossible for others. One thing that is stressed in all the service manuals I've seen is to follow ESD precautions (static "sparks"). It takes a discharge of less that 1000V to blow out an IC--this is not a spark you will even feel. However, you may have just not reconnected something properly. Again, the service manual helps with that. I would try to find a diagnostic program that you can install on a thumb drive and boot from that.

I hope I'm wrong and the damage is not permanent. Given the age of you laptop, you are really due for a new one anyway!

 

[acanicio]

Thank you for your reply AlHuneke..

I do have a bandwrist attached to ground when I work.
I do have the service manual and unfortunately it has no mention of the CMOS battery replacement procedure. I just used the procedure that most closely approached the goal, i.e. keyboard removal, and a couple of screws that are not even mentioned in the manual had also to be removed. This to emphasize the fact that the service manual is incomplete...

The old battery had gone down to 0,7 volts. The new one is 3.1Volts.
The computer was of course completely disconnected from mains when I did this. And as I already stated, it no longer has a main battery.

I've been doing this for now 35 years (started with an Apple II and a 8088 based PC XT) and have always had success building / upgrading / repairing computers, as it's part of my daily job.
I never had problems changing bios batteries in the past, I've actually changed hundreds of them,

I cannot be called a "youtube learner" as I started working in I.T. before even Internet got public.
Nevertheless I'm not a superman and may have missed something. And it's this something that I need to discover;

This being said, a thumb drive would be of no use, as the computer will not even post. No BIOS information appears on screen, nothing, even with an external monitor.

I now post this question just to seek advice if anyone has had this same issue with this same computer or brand, and if someone has come over it.
Just looking for ideas that I haven't thought of...

The three lock leds blinking must mean something, and the service manual does not mention anything about it. It doesn't even have a troubleshooting diagram or information.

I ruled out the power adaptor. I tried with my lab power supply unit set at 19.5V and the problem is the same.
The laptop draws 1.7 amps at 19.5V for the first 30 seconds, and then increases to 1.8 amps when the GPU fan accelerates to full. To me that seems normal.

One thing I noticed though, is that the CPU fan does not spin at all at startup. Only the GPU fan.
If I reckon well, both fans used to spin at startup...
Since I swapped both fans, I can also rule them out. Maybe a fan driver problem ?

Thanks again.
Best regards
Axel

 

[mrmike16]

I did a Bing search for "CLEVO W870cu Lights blinking", and the first result seems to mention something about the GPU - * OFFICIAL Sager NP8760 / Clevo W870CU Owners Lounge * | Page 271 | NotebookReview

But you've already tried removing it.

So I think the issue lies with the event that occurred right before this happened- The CMOS battery. You did not mention trying anything with it ever since you've replaced it. It may have enough voltage, but I think either there is some minor difference between the new and old batteries, or it was placed incorrectly (upside-down). You may have a lot of experience, but this kind of thing could happen to anyone. Just an idea. Or it needed some more time between the 2 to reset itself.

Maybe even try using it without the CMOS battery?

 

[acanicio]

Dear all,
I wish to thank you for your help.
Problem solved !!!

It was a problem indirectly induced by and proportional to experience : AGE !!
My VISION is slowly but surely rolling on a downhill slope...

I inspected all the connectors of the motherboard with my microsoldering microscope and I found a microscopic and almost transparent hair stuck in one of the memory slots... It was probably creating an incorrect connection on some of the pins of the DDR SODIMM module...
A swift swing of my microtweezers did the job. Reinserted the modules, turned the laptop on and TADAAAAAA !!! POST message !!

Sometimes it's just simple and earthly things that can make you send a good device whirling to the bin...

That's why a thorough and minute visual inspection is necessary before even thinking about ESDs and burned out components...

Thanks again !!
Best regards to all.
Axel

 

[mrmike16]

Dear all,
I wish to thank you for your help.
Problem solved !!!

It was a problem indirectly induced by and proportional to experience : AGE !!
My VISION is slowly but surely rolling on a downhill slope...

I inspected all the connectors of the motherboard with my microsoldering microscope and I found a microscopic and almost transparent hair stuck in one of the memory slots... It was probably creating an incorrect connection on some of the pins of the DDR SODIMM module...
A swift swing of my microtweezers did the job. Reinserted the modules, turned the laptop on and TADAAAAAA !!! POST message !!

Sometimes it's just simple and earthly things that can make you send a good device whirling to the bin...

That's why a thorough and minute visual inspection is necessary before even thinking about ESDs and burned out components...

Thanks again !!
Best regards to all.
Axel

I never, ever would have thought of a hair. Good job finding the solution, and thanks for posting it!