If you ground the D0 the chip will be always on.
Also to clear something up here. I have seen various reports of the DuoX 2 working as always on with nothing connected to BT. I am talking the original Blue DuoX 2 here. (Not tried a GS yet or a white). Well its not correct.
With nothing connected to BT on the original DuoX and DuoX 2 blue the box will FRAG, Tried 6 different chips whilst I was pissing around with an old Xbox.
Results
BT not connected to anything the Xbox FRAGs.
Connect it to pin 9 or the BT point it works
6 Chips in all. All the same result.
So.....first job for you is connect Xbox D0 to the D0 on the DuoX.
Connect the BT point on the DuoX to the correct BT point or alternative on the Xbox.
If it still FRAGs then you have an issue with the LPC soldering.
The install diagrams are in my signature