unplugged battery before nvme ssd upgrade and got "cmos checksum error"

[Rafi_sanjani]

I just replaced the nvme ssd on my HP envy x360 13 and before replacing it I unplugged my battery socket because I was afraid of a short circuit and after that every time I pressed the power button it didn't turn on, I had to connect the charger then the laptop screen started turning on with an error warning : "cmos checksum invalid, Reset CMOS 502". Then I click enter to continue rebooting the laptop, it boots fine, I have checked the system time in my bios and it's fine.

Can anyone help me why is this happening when unplugging the battery? Was my action correct to remove the battery before installing the new nvme ssd? or no need to remove the battery before upgrading the nvme ssd? Thank You

[Paul_Tikkanen · Accepted solution]

Hi:

Yes, your action to unplug the battery was correct.

That is part of the removal and replacement procedure set forth in the service manual.

That is the first step listed after removing the bottom cover...see chapter 5, page 36.

Remove the solid-state drive:
1. Disconnect the battery cable from the system board.

Maintenance and Service Guide HP ENVY x360 13 Convertible PCIMPORTANT! This document is intended for...

The cmos checksum error is normal because the main battery also serves as the CMOS battery which maintains the BIOS and system clock settings.

No more separate real time clock (RTC)/CMOS battery in notebooks with an internal battery like there are in notebooks with removable external batteries.