iPhone 11 stuck on update screen

What exactly do you mean by "attempting to assign as previous restore from previous phone"

Are you setting up as new iPhone or restoring from previous backup --> Set up your iPhone, iPad, or iPod touch - Apple Support

I tried to restore from a previous (iPhoneX) backup. First thing I had to do was update iOS on the new phone as my backup had the most recent patch while the inbox 11 did not. After that, the restore hung (I'm talking 3+ hours). Tried rebooting computer, same issue, tried recovery mode in 11, same issue.

BUT I solved it by putting 11 in DFU mode (if you dont know how, search online, there are many tutorials). I got an immediate "set up new iphone from backup" (or something like that) in itunes, and it worked - 14 minutes. Don't let the BS "how many photos do you have" throw you. I have easily several thousand and the number of photos is NOT the problem. I suspect some sort of software issue when you are restoring from an IOS version that is more recent than the out of the box 11 version.

TL;DR - if your black update screen gets hung on the 99%+ status bar, put your phone into DFU mode and restore from backup that way. I had a pretty large (120GB) backup and it took less than 15 minutes.

I should add the "how many photos do you have" is not from the software, its from several people on here offering answers indicating that may be an issue. It wasn't for me.