Replaced thermal paste and when booting I get a single flash of the power button for a second.

[Slomey]

 I have tried everything from re seating ram, trying with battery disconnected, checking fan connections and the only time I got it to power on I got the CMOS 502 Error. I took it to Best Buy and the guy said there was nothing he can do. I need to get this fixed so any help is greatly appreciated.

I am considering getting a new battery but since it doesn’t boot with the battery disconnected anyways I am not sure that would help.

 

  

[Nal_NR]

Hi @Slomey,

Welcome to the HP Support Community. 

I'd be glad to help you! 

I understand that you are having issues with the CMOS 502.

That is an excellent description and a great diagnosis. It is greatly appreciated.            

CMOS Reset (502) The CMOS checksum is invalid

• During the startup process, the system performs a checksum test of the BIOS. If the checksum is incorrect, the BIOS is assumed to be corrupt and the system installs a hidden copy of the BIOS to correct the problem, and the startup process continues. The following message displays for 15 seconds before the computer automatically reboots. You have the option of pressing enter to proceed without waiting 15 seconds.

• To resolve the CMOS Reset Error (502), restore the BIOS.
• Press enter to restart the PC.
• If the error displays after restarting, try to restore the BIOS using a USB drive. For more information, see the "Recover the BIOS using a USB recovery drive" section of the following:

For desktop computers, go to HP Desktop PCs - Recovering the BIOS (Basic Input Output System).

For notebook computers, go to HP Notebook PCs - Recovering the BIOS (Basic Input Output System).

If restoring the BIOS fails, contact HP.

Hope this helps! Keep me posted for further assistance

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