CMOS Checksum error 502

[Dario_Bas]

I''m having this problem since a while. when i turn off the pc and close it then it won't turn on again without the power cable (just for the turn on, then it works without it). When this happen the pc tries to turn on a couple of time failing and after some tries it shows the error CMOS checksum invalid error 502, it reset all BIOS parameters to default  and after that the pc finally turn on. This happen every time i  turn it off and close it. After that the date and time seems not to be update, so i tought that i shouls replace the CMOS battery but i found out that my pc does not require it. I also tried to update BIOS but it did not change anything.

The main problem with it is the reset of BIOS parameters, for example it put virtualization off, so i can't use any VM, and stuff like that. Also not being able to turn it on without cable is annoyng.

Thanks for help

[erico]

I suggest updating the BIOS to the most recent version to resolve a bad checksum issue.

Bad checksum means that there is some corruption in the BIOS firmware file.

I would have supplied a BIOS version, but you did not include which OS you are using.

https://support.hp.com/us-en/drivers/selfservice/hp-15-da0000-laptop-pc/20395828/model/32591056

All newer generation laptops use the main battery to supply current to the BIOS chip. There is no RTC or BIOS battery in your notebook.

Using Virtual Machines always requires it to be enabled in the BIOS manually, so updating the BIOS will always mean that is something you will have to do if you are a VM user.

[Dario_Bas]

As i said, i already tried to update BIOS to the most recent version, but nothing changed. About the vm, i know i have to enable it from BIOS, but before this problem i had to do it only once, now i have to do it each time the BIOS is reset. However the main issue is not this, but the fact that i can't turn it on without power cable. I forgot to say that the problem occured when i changed the the battery into a new one, but the new one is fully compatible.

Let me add, I use a Windows 10

[erico]

Since yours is a newer laptop model and since the BIOS settings revert to default each time the notebook is shut off, it means that your main battery needs to be replaced.

The main battery supplies current to the BIOS chip to enable it to retain the real time clock and settings.

Try resetting the EC (Embedded Controller) chip.

From a power off state, hold down the Windows key and the B key at the same time and press the power buttton. Keep holding down the Windows kay + B key for 11 seconds.