Display shows a lock icon or 'Lock'; buttons do not respond and settings cannot be changed

Safety first: No electrical work is needed.

Steps to troubleshoot:

• Check the user manual for the specific key combination to toggle child lock (commonly long-pressing the up and down arrows together, or a dedicated lock icon).
• In the Tuya/Smart Life app, open the thermostat settings and look for a "Child Lock" or "Keypad Lock" option; disable it.
• If the lock cannot be cleared, perform a factory reset from the device (note that this will erase schedules and Wi-Fi pairing).
• If the lock icon remains even after reset, the firmware may be corrupted; update firmware via the app or replace the thermostat.