I have a BV7-40 Mark III and offer the following suggestions:
Which remote are you using? If it is the Beo5 then there may well be a problem with the way the macros have been programmed. I use a Beo5 and can access the TV by pressing the SkyHD or the DTV text but ultimately it is the programming behind the text or graphic that matters. Go back to your dealer and get it reprogrammed.
If you have a Beo 4, try pushing the DTV button (which is on the latest versions) or the SAT button on previous ones. If you don't have a satelite system then you will probably be using the built in DVB tuner in which case these buttons are typically used. Depending on the rest of your setup and what is linked you may need to use the V.AUX option.
Recent power failures may account for mysterious behaviour but other than these points mentioned it will be an internal software/hardware problem that needs to be addressed by the installers so as the previous post suggests go back to your dealer.
That's the best I can offer you given my brief experience as an owner. Hope you find a solution soon. Best of luck.
Simon.
"We can rebuild him. We have the technology."
7-40, 7-2, 9000, BS3, BC2, LC2, BC6000, Beo5