Indoor unit displays temperature but does not respond to mode or temperature changes; stuck in one mode.

Safety first: No internal access is required initially.

Steps:

• Disable lock: Check the MrCool manual for child lock or function lock. Typically, holding certain buttons on the remote (e.g., '+' and '-' together) toggles the lock.
• Try another remote: If available, test with a different compatible remote control.
• Power reset: Turn off the breaker for 5 minutes, then restore power to reset the indoor PCB.

If still unresponsive: The indoor control board or IR receiver may be faulty and require replacement.