If the foliage is crispy all around, it's a goner.
It might be wise to still try and diagnose the initial problem so that you can prevent making the same mistakes again.
If it went crispy all at once with a few branches trying their best to survive, it's probably root death from asphyxiation.
If it was too dry for some time, it'll visibly struggle and branches will have brown foliage here and there.