Well, that gets into the "fruit of the poisonous tree" doctrine, but we're not doing a full criminal procedure law school course today . . .
Ironically, I heard more than one detective say that when they "dumped" a phone like that, they rarely found much useful evidence. There's just too much information on any given cell phone to be able to go through it all. So, in the end, their fishing expeditions end up being a waste of time and resources.
Litigation over the process, claims, and ultimately validity of the warrant happens after it is executed, where the product is used in a criminal case (one of the commonly argued problems with the FISA warrant process is that, because the products are not used in criminal cases, this never occurs, and because it is known that it will never occur, the constraints that the possibility of challenge places on both the conduct of executive agents seeking warrants and judges granting them also is missing.)