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Log out of the current HMI session and log in with manufacturer or service-level credentials (typically manufacturer password required).

Navigate to Startup -> NCU System Data -> General -> Date/Time and attempt to set the date and time again.

If successful, verify the settings persist after a complete power cycle (NCK and HMI).

Check user access level settings in the system configuration and adjust permissions if necessary for operational users.

Check for additional battery alarms (300500, 380600 series) in the alarm log that would indicate low battery voltage.

Measure battery voltage on NCK (X122 connector) and PCU/HMI battery - should read >2.9V for lithium cells. Replace if below 2.7V.

Power off the NCK/PCU before accessing battery connectors. Have replacement data ready as SRAM may lose configuration.

After battery replacement, reload backed-up machine data and parameter sets from archive or CompactFlash card.

Set date and time again through HMI Startup menu and verify persistence after full power down (30 seconds minimum).

Boot the HMI into service mode (hold down '5' key during boot) and run filesystem check utilities from the service menu.

Document all current settings and create backups before filesystem operations.

Check the CompactFlash card for physical errors - remove, inspect contacts, and test in external reader if available. Check for write-protect switch position.

From NCK commissioning mode, perform a consistency check of the NCK system files using 'System Data -> Consistency Check'.

If errors persist, perform a controlled software reload from Siemens recovery media matching your exact NCK and HMI software versions, then restore machine data from backup.

Software reload will erase customizations - ensure complete backup exists before proceeding.