iTunes restore didn’t work for locked iPhone 6s

I have an iPhone 6s that I recently did a factory reset to prepare to give it to one of my children. I didn’t do anything with it after the reset and a week or so later when I went to get it ready it is asking for a passcode. I didn’t remember setting one up but after trying every possible combination (and waiting days throughout all my times of being disabled due to entering the incorrect code) I attempted to do a factory restore using iTunes and a computer this phone has been synced with before. The restore appears to work on the computer but the phone takes me back to the lock screen instead of the initial set up menu. Any ideas of how I can reset it?