[Guy]

Perhaps you put in V.OPT 0, where it doesn’t respond to any IR commands.

To set back to V.OPT 1, with the TV in standby (red light):

On the Beo4, press the POWER button and LIST together.  Then press LIST until OPTION is shown, press GO (centre button), and then press LIST to show V.OPT.  Then press 1.  The power light on the device will blink to show that it has been accepted.

Then try MENU again and see if the TV responds.

Alternatively, have you tried MENU 0 0 GO to get back into the service menu, even if you don’t think the TV is responding to MENU?

EDIT:  MENU 0 0 GO should still work in BtB mode, and should then allow you to disable it.