CMOS Reset (502) Error and Date and Time problem.

[Roni1999]

I have HP Notebook 15da-0077tx laptop. I replaced my Laptop Battery few days ago from HP official store. After changing battery, when I am going to turn on laptop, it is showing...

The CMOS checksum is invalid. The CMOS will be reset to the default configuration and will be rebooted. Please check your BIOS Setup options to see if they change.

CMOS Reset (502)

Enter - Reboot the system

for more imformation, please visit:www.hp.com/go/techcenter/startup

After showing this message for 15 sec, the OS is booting. I also updated Bios. But, Problem doesn't fix. When I am going to turn on my laptop, it repeats. 

Also the Date and Time doesn't  work when laptop is off, i.e. When I turn on the laptop, it is showing the last date and time at the time of turning off. 

How to solve this Problem?

[Echo_Lake]

@Roni1999

Thank you for posting on HP Support Community.

Don't worry as I'll be glad to help,
I understand that you're getting an error on your HP Notebook. To provide you with an accurate solution, I'll need a few more details:

• Have you tried to update the Bios using HP Support Assistant?
• Have you tried to do a bios recovery on your PC?

Let's start off by performing a Hard reset on the notebook: 

Before power resetting your computer, do the following:

1. Disconnect or remove all peripheral devices. Startup the laptop and test the computer by itself, and then reconnect one peripheral device at a time.

2. Turn over the computer and look for a battery compartment door.

   • If there is a battery compartment, use the steps in Reset a laptop with a removable battery.

   • If there is no battery compartment, use the steps in Reset a laptop with a sealed or non-removable battery.

I recommend restoring the BIOS defaults. You could restore the BIOS with this document selecting the reloading the BIOS default settings. That way it will look at the Hardware installed on the Notebook.

Once done, restart the computer and check.

The best way to resolve this issue is to revert the BIOS to the previous working version and here's how you do it: 

HP Notebook PCs - Recovering the BIOS

Hope this helps! Keep me posted for further assistance.
Please click “Accept as Solution” if you feel my post solved your issue, it will help others find the solution.