I’d say it is most likely to be the switch on the PS.
I have had one which was less positive in its latching in the past. I’d try, with the PS disconnected from the mains, giving it a few firmish presses to ensure it is engaging and disengaging properly. Then power up again. A pencil with an eraser end is a good improvised tool to assist in freeing it. Obviously don’t press it too hard.
As Richard says, the button needs to be pushed right in, and if not pushed firmly enough it can fail to latch. So it’s best to use a firm (but not hard) push so that it works first time. It’s true that the XPS is particularly prone to blowing fuses, but gingerly pressing the button multiple times is only going to increase the chances.
Seriously though, the XPS is often reported as having blown its fuse, on power up. A search on here should find you plenty of examples. There was also an explanation as to why this is - but might be on the previous Forum version…? As I recall, the ‘right’ fuse value required to pass safety tests, was not perhaps ideal. But a higher value would have resulted in a failure of the safety tests…?
I had this problem with my 300dr not latching and found the solution on this forum. Push the switch in as far as it will go in the off position and hold it there. Then slide your finger off it and let it spring right out. Mine’s been fine since I did this but no guarantees !
It’s the XPS2/XPS DR. A higher rated fuse wouldn’t pass safety regs. The fuse used does but it’s right on the edge of it’s envelope. To that end you need to use the exact same make and type as Naim specify and use and with such a big Tx the current inrush is so high that it sometimes blow at switch on. Worth getting some spares from your Naim dealer.
Well, thanks to everyones ideas I’m up and running again! I turn off my system so infrequently I forgot how to turn it on. Followed Steve & Chris’s suggestions Totally missed the latching mechanism (!) Have a great holiday!