Ah that's interesting, I might try some of that with my 'dead' one then, before I give up on it.  Thanks for the link.  I have put it onto the dock which is connected to my PC and the PC is not recognising it, but I won't give up just yet.

As for the working Beo6 that I bought the battery for, still working, and the battery is still showing about 85%, so it's looking like a good battery so far.

I woke up a boot-locked BEO6 recently. Unit had a new battery but would not power on or show any signs of life on the charger. Config tool would not see it plugged in either. I had to use VirtualBox to emulate Windows 7 with the config tool and it woke right up. All signs pointed to completely dead but it just needed the right connection to the config tool.

You may be onto something there.  I got out my old Win7 32bit laptop which has config tool 6.84 already installed, connected the dock, and connected the 'dead' Beo6.  To my surprise Windows made the 'device connected' sound, and the config tool recognised it and created a new profile for it.  The Beo6 itself however did not light up, then after a couple of minutes on the dock, Windows made the 'device disconnected' sound, and I've had nothing since.

I tried installing the earlier 5.12 version of the config tool but got nothing from that, and I tried opening it up and disconnecting the battery (as recommended in B&O's service manual fort hr Beo6), then putting it back in the dock, but got nothing from that either.

The battery I got for the restored Beo6 was quite cheap though, so I'll buy another and see if I can get any further with it once it has a new battery in it.  The fact that it responded at all when I first connected it to the old laptop is telling me that there's some life still in it!

Thanks for the advice.

I tried a few Amazon/eBay batteries with no success. As soon as I installed the official part from B&O it worked right away and I've had no problems

The new battery I got from eBay has been in my working Beo6 for just over a week now.  I do use it every day (although admittedly not all that much), and it has spent a little bit of time in its dock connected to my PC when I have decided to alter the buttons once or twice, but the battery is holding up well - showing 75% now.

I ordered another one of the same battery to see if it will help reinvigorate my other 'dead' Beo6 but it hasn't arrived yet.  I'll let you know how I get on with that.

I did go to a B&O store on Saturday by the way, and asked about their ability to fit new batteries in a Beo6 (and also my Beocom 2).  They looked at me like I'd asked for a new wax tube for an Edison gramophone.

Tell you one thing though - I always thought the Beovision Theatre looked a bit ugly in the photos on B&O website but it isn't when you see it for real. It really isn't.

Something important to specify when talking about (third-party) battery reliability is how the remote is configured:

Some non B&O commands (namely Apple Remote IR commands) drain two of my Beo6 in five to ten clicks – Power Off, reboot, charge warning.
Same remotes last longer if I stay in the "Like no Other" universe.

The second Beo6 batter from eBay arrived today, so I put it in the 'dead' Beo6, charged it for an hour, then connected it to my PC.

It worked!  To my surprise it connected and a new profile was created.  No lights/screen came on but I had expected that from the advice given in the other post linked by Stoobie.  I created a basic configuration, hit the button, and lo-and-behold, the screen came on with 'No valid configuration' displayed.   It took quite a bit of time the firmware to update, but once it was done, the screen came on, my configuration was displayed, and it now seems to be working.  I haven't tested it fully yet as I have put it back on charge to charge fully, but it's looking good.

You were right Matador - there really is no such thing as a truly 'dead' Beo6.