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HP Recommended
Elitebook 840 G5
Microsoft Windows 10 (64-bit)

I have an Elitebook 840 G5 that will not boot unless I disconnect both batteries (CMOS and main), then hold the power button down for 1 minute, then I connect the A/C and everything works perfectly.  I can repeat this every time to get it booted.


When I get it powered up, I can power it down and connect the batteries and then it powers up and operates normally.  HOWEVER, if I power it off and WAIT a few hours (not sure number hours but over night for sure), I cannot power it up again unless I disconnect the batteries, hold the power button, connect the A/C and start all over again.


I am a engineer with 30+ yr experience with HP products but this has me stumped.  Here are things I tried and ruled out:

- BIOS updated to latest  version with default setting (maybe try older BIOS but I can't find one)

- I checked the CMOS battery and it is good

- I tested the A/C adapter with another HP laptop and the adapter/charger is good

- I wiped the drive and tried a clean install of Windows 10 and Windows 11 and did a Windows Update, plus I used HP Support Assistant to download and install HP updates.

- I just bought a HP Elitebook 745 G5 for a client and swapped batteries thinking maybe the main battery is bad, same problem

- I found new firmware updates on HP site that Support Assistant didn't find (Elan touch screen, Thunderbolt, etc.) and installed those updates successfully, but issue is still there

- Once booted, it can run on battery and it discharges and charges normally as expected

- I ran the built in HW diagnostics as well as the extended HP diagnostics and everything passes

- I can either close the lid or enter sleep mode for a few hours and then it powers up normally.


The problem appears if I leave the unit powered off overnight with the batteries connected.  The next morning, when I push the power button nothing happens, no lights, no noise, nothing, completely dead.


When I disconnect the batteries and hold the power down (45 sec seems to work too), as soon as I plug in the A/C, the power button lights up, the keyboard lights up,  I get a beep and the white screen complaining the CMOS is disconnected.  I press Enter to continue, it reboots and operates normally.


I have run out of ideas to try.

Any suggestions would be greatly appreciated






Accepted Solutions
HP Recommended

Hi Everyone,


I've been using the laptop at least once a day for over a month now and everything is now fine.

I closed up the case and everything is now normal, EXCEPT, that I must click on the new SHUTDOWN.BAT file icon I made to power off the laptop. (full shutdown)


The only strange thing is I can't have hibernation enabled and I can't use the regular shutdown.  The only negative is that it takes a bit longer to power up as it doesn't have the default hibernation / fast start to boot faster.


Thanks for all your help and suggstions



View solution in original post

HP Recommended

Hello Richard


you really did what was possible, it's diffucult to sugget you something more , last action seems to replace the motherboard.




HP Recommended

That was my original thought, but I tried more tests and I think it is the BIOS or a setting.  It still may be the battery as I only tested that for a few hours as the client wanted their new 745G5.


New things:

- Once I get it booted, I can connect the CMOS and leave the A/C connected.  Instead of doing a shutdown (or full shutdown via command line), I either close the lid, or click Power/Sleep.  The the next day, ie over 3 hrs, I can wake it up and all is good.


I noticed Windows defaults to 180 min (3hr) for hibernation.  I am currently testing it set to 999min, later I will disable via powershell.  Maybe it is a Windows setting?


Other things I plan on trying:

- try another NVMe drive and install Linux, see if it might be a Windows hibernation file corruption

- now that I downloaded and ran all the HP firmware updates (not found by Support Assistant, but found on the web), I might try a clean install of Win10 (or Win11) again

- I just received a new HP Elitebook 745G5 that has the same components (ram, NVMe, main battery, CMOS, same A/C), and this client won't need their new laptop for a week, I can swap out everything and see what happens

- I will try with the CMOS connected and main battery disconnected but using A/C, then I can try shutting it down and wait overnight (or 2 days) and then connect A/C and see what happens

- I will try to find an older BIOS version.  (I flashed to the latest BIOS twice but the problem persists). Any idea where I can find the previous BIOS version.


Worst case, I can use sleep mode and leave the CMOS connected (that boots faster, without CMOS, I get the error about the RTC and it reboot and then is fine) and use the laptop always connected to A/C.


Changing the motherboard is expensive and labour intensive.  I might just use it on A/C.

I have many other HP laptops (840 G3, Folio 9470m, even an old 6930p) and all work perfectly.


I'll keep posting the results of my future tests.


Thanks for reading about my issue.


HP Recommended

More info...getting closer to finding solution


I noticed the default Microsoft settings in the Power options for Hibernation is 180 minutes (3hrs) and that is around the time that I am having problems.  So, I set that to 999 minutes.  That is the max, if it fixes things, I will use Powershell to disable it.


In the meantime, I am trying to either close the lid or use Start > Power > Sleep to close the laptop.  So far, almost 2 days, this is working perfectly.  I have the CMOS and main battery connected and can run without A/C.  If I attach the A/C, the battery charges.


Another possible problem is the Graphics drivers.  While HP Support Assistant updated many things, it doesn't find everything on the HP support site for my Elitebook 840G5.  I manually downloaded the graphics drivers (344M) but when I try to install it, it expands the files into a folder as expected, but the I get the error message "This operating system is not supported".


I let Windows Update install Intel UHD 630 ver and it appears to be good.


However, I was testing the latest Adobe 2022 version of Photoshop and Illustrator that were released this week.  Photoshop seems ok, but when I launch Illustrator, it warns that my graphics drivers are out of date and I should up to v100.9168 or later as the current driver will be unstable.


So, how to get the latest Intel drivers?  I went to Intel.com and found ran their Intel Driver & Support Assistant and let it scan my system.  It found that I need THREE new drivers as my system might have issues.  The graphics are now on ver 30.x.x.



Why is HP Support Assistant missing so many KEY files that I need?

Why is the HP website for my model not posting the proper Graphics files?


I plan on downloading the three Intel drivers and then install a new NVMe SSD and start from scratch with a clean install of Windows 10 (and/or 11) and manually install the drivers.


I'll keep everyone posted.


HP Recommended

Very interesting! 

Whenever I set up a new system this is my first command:

powercfg /h off

The hiberfil.sys is a terrible file. 

HP Recommended

Thanks for the tip.  I am trying it out now.


I ran that from an elevated Command prompt.  Do you enter it that way or via Powershell?


I found older BIOS (from version 1.14 through the latest 1.17 and will try those too.  I still have a lot of tests while I have the new 745G5 laptop for a client (I will borrow the batteries, ram, and A/C from the new laptop).  Problem is each test has many combination to try plus I have to wait 3+ hr before I can try powering up.


I will keep everyone posted.



HP Recommended

Yes, elevated command prompt.

The hyberfil.sys should be deleted.

reboot and execute these 2 commands also:


DISM.exe /Online /Cleanup-image /Restorehealth

sfc /scannow


These commands check the system for corrupted files

HP Recommended

I remembered to run the SFC (it is clean) but I forgot about DISM (just ran it and is clean), thanks for the reminder!

Then I ran "powercfg /h off" and rebooted.

When I looked for hiberfil.sys, I couldn't find it (I checked hidden/system too), so I guess the command deleted it.


I restored the BIOS to the latest 1.17 version and left the main battery unplugged (for these test) but left the CMOS connected.

With A/C, it boots normally.  I waited an almost 2hr and it boots normally.  I shut it down and will wait 3+ hr and see what happens.


I like your tip about deleting the hibernation.  Makes sense, especially for desktops.


I'll let everyone know my test results by tomorrow.  I still have many combinations to test out (connect battery, try Windows 10 - currently the SSD have Win11, try new main battery, etc.)


Thanks for the tips!

HP Recommended

I ran powercfg.exe /h off and it seems to help a lot!


But, I had to disconnect the CMOS (RTC battery).  Once I disconnected both batteries and booted (many tests show I can hold the power button down to just a few seconds) and it will boot connected to A/C.  Then I power down and connect the main battery but leave the CMOS unplugged.  Now I can run on battery for days.  It almost seems resolved, but I am not sure what the problem is.


I have tested the laptop for over 4 days now.  I can power it up and shut it down after 3hrs, overnight, the next day.  All is normal, but the CMOS is disconnected.


I changed so many things during my tests that I am not sure what fixed it.  So, today I replaced the working NVMe drive and booted from the latest Win11 ISO image.  Now I will try these variables and wait 3hr and overnight and see where the problem is.  I am leaving the latest BIOS v1.17:

- boot from USB, wipe drive, don't connect internet yet so the graphics is 'basic' and run on fully charged battery but no CMOS

the only change I made was running "powercfg.exe /h off" elevated command

- next: let Windows Update download and install all the Intel updates, then reboot and retest

- next: install the latest Intel Graphics drivers (The HP site and Support Assistant don't work)


Lastly, I can pull the CMOS battery from a new HP laptop (745G5 same series) and try that.  I did test the existing battery and it shows good, but one can't be 100% certain of anything.


Worst case, I leave the CMOS permanently disconnected.  It appears I can run on A/C or battery but the CMOS must be unplugged.  If it gets screwed up again, I can open the case, disconnect battery and unplug A/C, wait a few seconds, connect the battery and/or A/C and work as normal.


Strange, but at least I didn't waste money on a new motherboard and/or main battery as those are not the problem.


I'll post my results, but it will take a week to know for sure.


Thanks for all your tips

HP Recommended

Hi Everyone,


I think I now have a working solution.....


Since my last post, I connected the CMOS and main battery and it boots up every time.  However, I MUST DO A FULL SHUTDOWN (ie run bat file with shutdown /s /f /t 0).


So, to summary: once booted, I install a clean version Win11, update drivers (HP and Intel), then disable hibernate, create a desktop shortcut to run a FULL SHUTDOWN, and never use the normal Start > Power > Shutdown mouse options.


With both batteries connected, I can power up use it a bit and then do a full shutdown at least twice a day for a week with no problems.

Then after a week, I couldn't power up, but when I unplugged both battery and reconnected, I noticed the battery had run down so that was probably the problem.


So, i connected the AC to recharge.  It has been powered up twice a day (left on for 5-15 minutes each time) and fully shutdown, all with no issues.  The battery is down to 10% and it is complaining I should connect the A/C.  I'll wait a few days to make sure the battery is dead, then connect the A/C and try powering on.


If that final test works, I can finally replace the bottom covering (if have been loose for month while I test to make unplugging easier) and tighten all the screws.



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