Turn on your device,
select menu item "Unlock",
enter your PIN-code.
More details in your manual.
If your Lucia N°03 Home Portal identifies this PIN code as "wrong," then you may have mistyped it.
However, if your Lucia N°03 should display a Web-Code (8 digits) again, log in to your PIN manager and go to "registered devices".
On the right below the "actions" field you will find the "Generate new PIN code" button and click on it.
Follow the instructions. Do not switch off your Lucia N°03 Home Portal in the meantime, as you will need the web code shown.