IBM System x3550 M4 Installation And Service Manual page 701

W.68002 [W.68002] A CMOS battery error has been detected
Explanation: CMOS Battery Fault
Severity: Error
User response: Complete the following steps:
1. If the system was recently Installed, Moved, or Serviced, makesure the batter is properly seated.
2. Check IBM support site for an applicable service bulletin or firmware update that applies to this error.
3. Replace CMOS Battery
4. (Trained Service technician only) Replace the system board.
Appendix B. UEFI/POST diagnostic codes
W.68002
683