Chosen Solution
My iPhone 6 fell of my couch and ever since it wouldn’t turn on. The display was knocked loose so I had to push it back in, and I could see that the back light was on so I tried to restart it, and it didn’t work. Now it just won’t turn on at all. iTunes recognizes it when I plug it into my computer, but it just wants to restore and update, which I do, but as soon as I turn it off and plug it back in, it just wants to restore and update again. Anyone have any suggestions or is it just a lost cause?
Take it to a phone repair shop for repair evaluation. It’s best to do it this way so that you don’t end up buying a replacement screen with the risk of it still not working after that. This is probably leaning to be a board level issue if it shows up as being in DFU mode. You can find out if it is by installing 3Utools via 3u.com then running the application and plug in the phone. If it does say DFU mode there is a hardware fault with the phone.