Main server switch blew which took out the rack power, fuse, UPS fuse etc.
All had to be replaced. Got a switch upgrade at the same time.
C4P was the last server to be checked I'm afraid. Didn't start up as the config - which only gets run on restart - was out of date as some services had already moved to another server and the nginx config was looking for them by mistake. You only get to find these things on restart!