With most modern B&O products they have a pin code which has to be entered if the TV is unplugged from the mains power for more than 30 minutes. If you try and guess more than three times incorrectly, you then have to wait a further 3 hours before trying again.
If you do not know the pin code, you will have to call the local B&O dealer. They may not give it to you because you are not the actual customer, but call anyway.
Keith..