Hey
Tesltra don't own the NBN equipment. You might have to take it up with NBNCo.
I agree with you re the battery. My next door nighbours alarm went off, and it turned out the battery had failed, and they had to wait for a tech to come out to replace it.
I would not be messing about with the PSU just yet, but I'm sure others have started to fiure it all out.