iPhone 7 boot loop is going on and I have tried everything and this error 4013 keeps coming up

This support document will help you. Try these steps.

If you see error 9, 4005, 4013, or 4014 when you restore your iOS device - Apple Support

If you do not succeed, contact Apple as suggested in the document.

Contact - Official Apple Support

Go back to Apple as soon as possible. They have to check it again.

Same exact issue (iPhone 7, latest iOS), and I can't even exit recovery mode or enter DFU mode without the iTunes connect screen coming up, and without iTunes consistently failing to update AND restore. What seems to happen is that the progress bar appears for a split second as it tries to restore, only to have the screen turn off again and turn back on in a few more seconds, continuing its nonstop boot loop. It seems like the boot loop INTERRUPTS the attempt to restore it. I Would rather not waste days of time and money making appointments 45 minutes away at a Genius Bar, so if anyone knows any unconventional solutions for this, at least temporary, let me know.

Okay, filling out the form to sign up for a repair / Apple Store service indicates that it will cost me over $300 because I'm six months past warranty, and my Verizon plan won't give me another cheap upgrade until September. I've had my iPhone 7 for a measly year and a half and haven't dropped it on any hard surfaces or gotten it wet, and I've kept it covered during my entire ownership. Nor have I jailbroken it. All I can say is that it had a few non working legacy apps on it -- Tron, Midway Arcade, Karate Champ -- that I was hoping would one day be updated for iOS 11. Not very impressed with this situation. If we find out that something in the nefarious iOS 11.2.6 has caused this, Apple has a lot to answer for.