CMOS CHECKSUM BAD | Firmware settings invalid

What This Code Means

Where Users Usually See This Code

• During POST at startup
• Firmware security checks (TPM/Secure Boot)
• Boot device selection and initialization
• Hardware monitoring screens

Why This Code Appears

• A required component did not initialize correctly
• Boot configuration could not find a valid device
• Security policy blocked boot
• Firmware detected a health or configuration issue

What Typically Happens Next

• Boot may stop or loop at startup
• A firmware message is displayed
• The system may enter recovery or setup screens

What This Code Is Not

• It is not safe to guess at hardware fixes
• It is not always solved by a firmware update

Troubleshooting Checklist

• □ Record the exact message and the device model
• □ Check official documentation for the specific OEM mapping
• □ Confirm boot order and whether the expected drive is detected
• □ Verify date/time settings if security validation is failing
• □ Avoid hardware disassembly unless qualified and instructed
• □ Use vendor support pathways for repeat boot failures

Notes And Edge Cases