That sounds quite bad, what kind of plug does the nano use? I assume it's a step-down transformer?
The question is, wether it was the transformer or the socket that caused that to happen, I'd hazzard a guess that those transformers are not fused - probably not even thermally - so if that's gone wrong I'd be looking for another one to replace it, though I think it's more likely that the socket it was plugged into has a loose wire behind it, if you're in a council house it pretty much a guarantee they'll have cut corners somewhere. If the breaker went it sounds like an overload or a short - I trip breakers a lot, which reminds me, if they keep going off, look for the source of the problem instead of taping them in the "ON" position, otherwise things seem to set fire for some reason.
Probably unrelated, but I heard there's a solar storm causing a lot of radiation that might affect electrical systems, though I don't think it has anything to do with this, I do wonder what - if any - effect it will have on the Wireless providers.
