The gods love a pious acts because it is beloved by the gods. But it has been agreed that loving explains being beloved, contratry to the conclusion 3. Since 3. follows from 1. and 2., either 1. or 2. And since Euthyprho has accepted 1., premise 2. Being beloved by the gods is merely a characteristic of the pious, not what the pious is.
Some numbers are odd, but all odd things are numbers.
So to be odd is to be a number of a certain sort. This kind of account appeals to a more general notion than that under consideration. In the case of piety, Socrates proposes that it is a part of justice, to which Euthyphro adds, it is that part of justice which is concerned with the care of the gods. The other part is that which is concerned with the care of humans. This new account really only pushes the problem back a step.