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HP Spectre x360 running Windows 11 displays the following errors during startup:
Error 502 – CMOS
Error 602 – Battery
These messages may appear on a black screen during system startup.
Applicable Products
HP Spectre x360
Other HP notebook PCs that display CMOS Error 502 or Battery Error 602
Operating System
Microsoft Windows 11
The issue may have one or more of the following symptoms:
CMOS Error 502 appears during startup.
Battery Error 602 appears during startup.
The computer may continue to boot after displaying the errors.
BIOS settings may be reset or changed.
The system may report a battery capacity or battery health warning.
Error 502 indicates that the BIOS CMOS checksum is invalid. HP indicates that this can occur when the BIOS checksum test fails, and the system may restore a backup copy of the BIOS automatically.
Error 602 indicates that the measured storage capacity of the secondary battery is less than 25% of its original capacity. The 602 number is the diagnostic error code recorded in the system log.
A CMOS/BIOS issue and a battery-health issue can therefore appear together, but they represent different diagnostic conditions.
1: Perform a Hard Reset
Shut down the notebook.
Disconnect the AC adapter.
Disconnect all unnecessary USB devices and peripherals.
Press and hold the Power button for approximately 15–20 seconds.
Release the Power button.
Connect the AC adapter.
Turn on the notebook.
Check whether Error 502 and Error 602 appear again.
The hard reset removes residual electrical charge and can help resolve temporary startup or hardware-detection issues.
2: Run HP PC Hardware Diagnostics
If the errors continue:
Turn off the notebook.
Turn it on and immediately press Esc repeatedly.
When the Startup Menu appears, press F2.
Open HP PC Hardware Diagnostics.
Run the Battery Test.
Run the available system/component tests.
Allow the tests to complete.
If a Failure ID is displayed, record the Failure ID.
3: Interpret the Battery Test
If the battery test reports a failure:
Record the Failure ID.
Verify whether the affected battery is the primary or secondary battery.
If the battery has significantly reduced capacity, battery replacement or service may be required.
HP identifies Error 602 as a low-capacity condition for a secondary/external battery when its measured storage capacity is below 25% of its original capacity.
4: Restore BIOS Defaults
If the battery diagnostics do not identify a hardware failure, restore the BIOS defaults.
Turn off the notebook.
Turn it on.
Immediately press Esc repeatedly until the Startup Menu appears.
Press F10 to open BIOS Setup.
Select the File tab.
Select Apply Defaults and Exit.
Confirm the selection if prompted.
Allow the notebook to restart.
Check whether the CMOS Error 502 returns.
5: Update the BIOS
If the notebook successfully starts Windows but Error 502 continues to occur:
Identify the exact notebook model.
Go to the HP Software and Driver Downloads page.
Locate the BIOS section for the notebook.
Check for a newer BIOS version.
Install the BIOS update according to HP's instructions.
Restart the notebook.
Check whether the error is resolved.
6: Check the Date and Time
After restoring BIOS defaults or recovering the CMOS:
Start Windows.
Check the system date and time.
If the date or time is incorrect, set it to the correct values.
