Microwave shows 'C-d0' and will not start, often after a power interruption.

Safety: Ensure the unit is plugged into a grounded outlet.

• Disable child lock: On many Samsung models, press and hold the STOP/CANCEL or START button for 3–5 seconds until the lock icon disappears. Refer to your user manual for the exact key combination.
• Power reset: Unplug the microwave for 5–10 minutes, then reconnect and check if C-d0 clears.
• Check door: Open and close the door firmly several times to ensure the switches actuate properly.
• Service: If the code persists and the child lock is definitely off, the door switch circuit or control board may require professional diagnosis.