Hi Adrian,
No hotspot as I can't leave the Onion2+ connected very long as it would melt my desk 
I didn't connect it to the dock the wrong way round as it worked before I plugged in the expansion boards and I haven't separated it from the dock since.
Andy
OK, thanks that's interesting and useful to know. The temperature of the metal casing is very hot it would probably remove my skin if I didn't let go pretty quickly. Is that in any way comparable to yours?
The other more telling sign is that where the Amber LED had previously lit all the time it's now dark all the time....
I finally got round to getting started with my Onion. I plugged the Onion 2+ into the Expansion Dock and it appeared to work in that the amber LED came on solidly and stayed on. I didn't have Bonjour installed on my Windows PC so I installed it and restarted. At the same time I turned the power on the board off and plugged in the Ethernet Expansion board and the OLED Expansion board that came with it. When I turned the Onion2 on this time the Amber LED didn't light and the metal case on the Onion2+ got very hot. Even if I just use the Onion2 on the Expansion Dock now the Amber LED doesn't light (the one on the dock pulses on) and the case gets very hot.
I presume it's dead?
Andy