What will happen if N.Korea test another nuke?

With all that's going on in the world, it's begining to look like N.Norea are planning ANOTHER nuclear weapons test!

What happens if

a) They test one but it only "fizzles" like the other one?

b) They test one which has a more improved kiloton range?

c) They test a nuclear bomb ABOVE ground

Sadly I think its pretty likely they will. Especially as the first one is being 'played' as a kinda failure in the media. Plus NK seem to think nobody is taking them seriously enough!

Of all the global issues at the moment, I think this is the one that nobody has by the tail.