If it was running fine and has just started mucking about, then my guess is not the psu (as others also don't work), but perhaps the fan? Is the fan switching on at all? If not it could be a built in shut-off when the temps get too high. Do the green lights on the boards come on at any stage i.e. do they start hashing before they turn off? These chips heat up very quickly and if there's no cooling it should shut off (I would hope). Can you get the fan to run at full speed by removing the blue wire?

You could also try unplugging both boards and just starting up the controller board to see if you can connect to the gui, or if that's your problem.

Edit: oops, just realized you can't run the controller board, without supplying it with power somehow...