Hello. To answer your question it would be necessary to have access to the text that it is related to. As you did not provide the text, it is not possible to provide an exact answer, but I will try to help you in the best possible way.
Metaphor is always used to create a new meaning, through comparison. The goal of the metaphor is to expose something very expressive and of deep and well explored meaning. For this reason, it would be necessary to have access to the entire text, so that it was possible to understand the meaning of "struck by lightning".