Display shows L1 or a lock symbol; buttons do not respond to presses.

Safety first: This is typically a user setting, not an electrical fault. No internal access is required.

Step-by-step checks:

• 1. Try unlocking sequence: On many Gram freezers, press and hold the lock or alarm button for 3–5 seconds until the lock symbol disappears. Refer to the user manual for the exact combination.
• 2. Test buttons: After unlocking, press other buttons to confirm they respond. If some buttons remain unresponsive, the keypad or display PCB may be faulty.
• 3. Power reset: Unplug the freezer for 5 minutes, then reconnect. Try the unlock sequence again.
• 4. Inspect for moisture: If the control panel has been exposed to condensation or cleaning fluids, allow it to dry completely and test again.

When to call a technician: If the panel remains locked or unresponsive despite following the unlock procedure and power reset, the display PCB or keypad membrane may need replacement by a technician.