Bios checksum invalid (cmos reset 502)

[Alin1983]

Can enyone help me to fix this issue?

Thank you in advance.

[Fanordi]

Hello, how old are your PC?? If your PC have pretty years and if your battery is not charged, your CMOS battery can be down and maybe need to be replace.. 

For more informations please give me your product number (P/N):

Locate your product's information label

[Alin1983]

Hello, first I sant to say thank  you for tour rapid respinse.

The product P/N: [edit]

I brought it 6 years ago from Italy. 

Perhaps you have right regarding the battery.

I don't know how to replace it, where is placed. 

[Fanordi]

Hello, if you charge your batterie to 100% and shutdown your PC, when you restart the PC do you have this error?? 

[Alin1983]

To be honest I didn't use it with the battery for a long time, only monthly to change it.

But I observed one think, when I keep it with the battery  attached or with the power supply when I restant it the bios error not comes .

[Fanordi · Accepted solution]

I think so your CMOS battery is dead and need to be replace. 

I don't find your model with your serial number, I need your product number (maybe in the same label).

[Alin1983]

I willy try layer to open it and check the voltage for the cmos battery, now I am to some courses and also I don't have the tools to solve this. I am almost shure also now  that I will need an Cr2032 battery.

Thank you!

[Fanordi]

You can go here for search your product page, and find your "maintenance and service guide". This guide can help you to open your PC and locate your CMOS battery.