I can speak to the iPhone 7 and one model of iPhone 8 . There is an article published by apple on a board level failure triggered by updates after iOS 11 . I took two iPhone 7 to the apple store today after a tech at T-Mobile showed me the article . Apple will fix any phone affected by the update cellular problem on the listed models . 1660 is the one we had . They said they will replace the boards and the battery and possibly the screen if needed . All this at no charge even without apple care . Sorry I didn't save the article but it was published in 2018 . Like I stated, they did the repair today on 11/24/19 .