No one can know for sure. Certainly the US did not know what was happening since it was looking for the drone outside of Iran. If it malfunctioned and went awry, most likely, it would have destroyed critical electronics when it crashlanded. Note the landing gear was hidden from view and clearly the wings had come off and were pasted back on. Iranians may have fabricated the story of gaining control. When will they get the next one?
Australian police arrest 5 over shooting 'linked to terrorism' (Reuters)
from the article: Obama asks Iran to return downed U.S. surveillance drone