Display shows E12 and the refrigerator may show erratic temperatures or intermittent operation after a power event.

Safety first: Disconnect the appliance from mains before accessing control boards.

Step-by-step:

• Power cycle: Unplug the fridge for at least 10 minutes to allow capacitors to discharge. Plug back in and observe if E12 reappears.
• Check supply: Use a surge protector or dedicated outlet to prevent future corruption from power spikes.
• Inspect control connections: Remove the top cover or control panel to access the display board and its cable to the main PCB. Reseat all connectors.
• Factory reset (if available): Some models allow a user reset via button combinations (consult the user manual). Perform this to clear minor memory errors.

Action: If E12 persists, the main control board likely needs replacement and should be handled by a qualified technician, as reprogramming may be required.