In the former case, you will hopefully have flipped a 2 or 3 (or, if you're really lucky, multiples/both). Any row/column in which you have flipped a 2 or a 3 needs to be re-checked to see if there is any way that row/column can contain another 2 or 3 - if it cannot, it is dead. So, for example, if you flip a 3 on a 6/1, that row needs to get 3 more to reach the total, and it needs a Voltorb, in 4 remaining squares - so it is dead, because it must be 1/1/1/Voltorb. Likewise, a 2 on a 5/1 renders that row dead. A 2 on a 6/1 does not help, and so forth.