Hello Ya'all folks!
I was passing by and I saw this topic that caught my attention
Just as a suggestion mate, if the restore process doesn't work but you still need to reset the whole phone. . . iCloud might help this time
There's a slightly chance to wipe it clean and start all over. . . if you do use iCloud with your device remember you can always erase it
remotely and then the iPhone will shut down, erase and get back on the initial setup to get started OOB (like out of the box)
Note.
Keep in mind sometimes if you use BETA iOS versions that might be the problem . . . if so follow About iOS beta software - Apple Support
I'm just saying that's another way to reset it back to factory just in case iTunes can't do it . . if that's what you're looking for, otherwise if you can't restore the device via regular methods then I suggest you to follow BBoiss advice and mail it or carry the device to the store to have them take a look at it, there's a chance
it could be a hardware issue with the logical board or any other pierce of hardware
Hope it helps
Dr macOS
Apple Support Communities
An apple a day keeps the doctor away!!!