iPhone 6, iOS 11 boot loop/restore bar loop I have a problem with my iPhone 6. It randomly went off, and when I tried to power it on again it became stuck on boot loop (Apple logo is displayed, going black, and Apple logo is displayed again) over and over. I've done some research, and I tried all solutions, such as restoring the phone via iTunes, ReiBoot, and other similar software everything goes fine, but when progress bar is displayed on the phone, it stuck, and it is not moving at all.

I don't have any idea what more I can do more...
Now that you have confirmed an Error 9 message with iTunes, I can say with certainty that you're NAND IC (that is the chip that has all of the data) is corrupted. This requires removing the NAND and reprogramming it with a specialized tool like this one, reballing the IC and then re-soldering back into place. This will mean that you will lose all of your data so hopefully you have a backup of the data.

This is not a DIY repair, you will need to find a repair shop that does micro-soldering repairs.