Solution 1:

Many things can cause a boot-looping device.

Try these things (if you haven't already) to see if anything helps:

  • Try a hard reset (Home & Power button for 10 secs)
  • Use a genuine Apple Lightning connector
  • Use a genuine Apple charging brick and let it charge overnight
  • Try to connect it to different computers (mac/pc if possible) with an updated iTunes
  • Put the phone in recovery mode (search DFU Mode). Careful, this can reset your data
  • Use 3uTools for putting it in and out of Recovery Mode
  • Use 3uTools to flash the firmware (you can't downgrade)

If you are comfortable opening your device (now that it's out of warranty) then consider the following:

  • Disconnect the Front Camera Ribbon from the logic board and reboot your phone
  • Disconnect the screen assembly completely and see if iTunes will recognize the phone.

Otherwise, you may have a logic board issue. If you are uncomfortable doing these steps, consider either doing an OOW replacement at Apple or finding a reputable, independent repair shop to do the troubleshooting. A shop that also does micro-soldering can go deeper if the problem is not modular in nature.

Solution 2:

The next best thing is to restore the iPhone software. Meaning erase the software and then using iTunes on a computer to restore the software with a refreshed iOS 11.0.2.

Backup iPhone via iCloud (optional but highly recommended)

Plug in iPhone to iTunes and click restore iPhone. iTunes should also automatically backup the iPhone also. - https://support.apple.com/en-ph/HT201252 **Make sure iTunes is up to date and then restore.

Once restore is done you are going to get the hello screen on the iPhone. Set up the iPhone properly then when you get the Apps & Data screen, restore from iCloud backup (unless you chose not to back it up). - https://support.apple.com/en-ph/HT204184

Then your phone should be back up and working with your stuff back on it and the software cleaned up.