CMOS checksum invalid error/BIOS update

[Liliana06]

Hi, 

For the last week or so, I've gotten the CMOS checksum is invalid error, and it's asking me to check my BIOS. The first time happened after my computer had completely died, and so I ignored it. The second time, my screen froze, and so I turned my laptop off, and when I turned it back on, I then received the same message. This led me down the rabbit hole of solving the issue. It led me to the HP support website, where I could find a BIOS update to download. Now, it didn't offer me a version for version 25H2, so I simply chose the Windows 11 option and downloaded it from there. After that, I assumed everything was fine, but once again, my screen froze, and so I manually updated my graphics driver, and I thought all was well. Once again, the error popped up, and I went back to the HP support website and downloaded the newest one, which I'm not sure why it wasn't there already, and as far as I know, the latest BIOS update is May of 2026. As of yesterday, I was moving some mods around, and my screen started flashing between my file explorer and a black screen. Eventually, this led me to shut my computer down once again and not be able to turn my laptop on for hours. Finally, I was able to get it back on later that evening, and once again got the error. I feel like I've gone down many rabbit holes and still nothing has led me to the correct information, and I feel lost at this point. Can anyone point me in the right direction, or maybe tell me where I can find the correct BIOS update, so this stops happening? Thank you for any support.

[Paul_Tikkanen]

Hi:

That error can normally occur due to a problem with the battery.

There is no separate CMOS battery in most notebooks that come with an internal main battery.

So, the main battery is responsible for maintaining the BIOS and system clock settings in place of the separate CMOS/RTC battery that older notebooks with external batteries have.

I recommend that you test and calibrate the battery.

HP Notebook PCs - Testing and calibrating the battery (Windows) | HP® Support

As for providing the link to a possible BIOS update for your notebook, I would need to know its full model number or product number.

[Liliana06]

Hi, I appreciate your reply!

I've yet to attempt the battery and recalibrate test, but in the meantime, this is my product number 9S1R6UA#ABA

I'll be sure to reply back after I do the battery test.

[Paul_Tikkanen · Accepted solution]

You're very welcome.

According to the product number you posted, you have a  HP Envy x360 16 inch 2-in-1 Laptop PC 16-ac0000:

HP PartSurfer

Below is the link to the latest BIOS update HP has for your PC (F.07):

HP Envy x360 16 inch 2-in-1 Laptop PC 16-ac0000 (8Z200AV) Software and Driver Details

[Liliana06]

I just downloaded that BIOS update, so hopefully everything works fine from here on out.

I also the computer did pass that battery test, so hopefully all is well.

Thanks again for the help and support.

[Paul_Tikkanen]

Anytime. 

Glad to have been of assistance.