Washer-dryer combo powers on but will not start any cycle; the Start button does nothing.

Safety first: Ensure the drum is empty of loose tools or objects before attempting to start a cycle.

• Check for child lock: Look for a key or lock icon on the display. Disable the child lock by holding the designated button combination (refer to the user manual; often pressing and holding two buttons for several seconds).
• Verify door closure: Close the door firmly until it clicks. If the door icon does not indicate 'closed', inspect the door lock and strike as described in E6/E11.
• Test other buttons: If some buttons respond and others do not, the control panel membrane or PCB may be failing.
• Power reset: Unplug for 5 minutes, then reconnect and try again.
• Call a technician: Persistent non-start with a good door lock and no child lock suggests a faulty UI or main PCB that should be professionally replaced.