Elitebook 840 G5 i7 CPU stuck at 0.4GHz after BIOS update to version 01.26.00 Rev.A

[MattMieszko]

I followed the instructions but the device did not reboot successfully and power button seems to have no effect- all is dark apart from the blinking orange LED next to power supply input;) just like mentioned here: https://h30434.www3.hp.com/t5/Notebook-Video-Display-and-Touch/Laptop-power-button-blinks-when-I-try...
I'll try to get some other bios from different computer

 

 

[BeemerBiker]

There is something very wrong.  The more I think about it the more I believe your problem is thermal shutdown. Either the temperature is actually too high or the CPU is getting an incorrect value or no value, and shuts down to lowest speed.

Try putting that 1.26 back in using the USB flash.

Did you do any board level work such as removing the heat sink and replacing the cooling compound?

Is there a part number on the motherboard that identifies it?  It should look similar to this motherboard.

Go to the below site and enter the serial number of your system.  Look for the part number for the system board and verify that your motherboard has the same part number that is in the parts list. THE MOTHERBOARD IS USUALLY,  BUT NOT ALWAYS LISTED.

https://partsurfer.hp.com/partsurfer/

Looking at your manuals and guides list here, it appears you have sure start.  It is discussed in several documents (white papers)  What happens when you tried the WIN key + "B" ?

Click here to see how to recover your BIOS. Do 1, 2, and the first part of 3.
For the second part of 3 that would be the USB flash with 1.26

If the motherboard Part Number does not match the Part Number shown by the serial number of your system, try to return it. 

I do not know what else you can try.  There is some hardware problem and even a bios flash may not fix it

[MattMieszko]

L15522-601

Thanks for the reply and efforts so far;) 

I'll try returning to the 1.26. 

Thermal shutdown is possible, although I did not do any board-level work mentioned - the only thing I did was remove the bottom cover and see if the fan spins, then disconnected the fan, removed the battery and RAM, tried different boot procedures to reset any software faults that might have occurred but no I did not see anything wrong with the board, no smoke or spillover signs. 

The motherboard picture is attached. Serial number: L15522-601, appears in parts Surfer as 

SPS-MB UMA i7-8650U WIN

Win+B or Win+V does nothing - the system used to normally boot up. Now it's just black screen, power button does not even blink.

I'll just scrap the laptop for parts then, battery, SSD, RAM, display and keyboard are in good shape. Fan also works.

[MattMieszko]

Huh it came back to life after removing RAM and battery:) but still showing 0.4Ghz

 

[Cm138]

Is there any progress on that? I have exactly the same issue.

The only difference to your story that I was changing the SSD  before updating the firmware when the slowdown happened.

However, as I now reinserted the old SSD and the issue still exist I expect that the problem is connected to the firmware update rather to the SSD change.

[MattMieszko]

Nope, I’m waiting for exactly same model and will try to dump the bios from there. Should have it sometime next month