The CMOS checksum is invalid.

[Zabakuma]

Hi, 

I have problem with my  GP Envy x360 15,6. Starting very slow, there is black screen quite long and when starting have a message for short time.

"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 changed."
CMOS Reset (502)
ENTER - Reboot the system

What that mean? How fix it?

[Fanordi]

Hello, you can execute an hardware test in your computer. For this, restart your computer by tapping F2 when it is been down for restart. You come in HP Hardware Diagnostic Interface and can execute all tests. If you have a fail please tell us. 

For more information about HP Hardware Diagnostics please see this: 
https://support.hp.com/us-en/document/c03467259

It is maybe a probem with your CMOS battery.. How old are your PC??