iPhone 7 I was gifted does not restore

Hi all, less than a month ago I had a friend who decided to gift their iPhone 7 to me in okay physical condition for me to experiment on, however, they had set up something called turdus merula on it to use a tethered downgeadd and forgot to re-update the phone before giving it to me (there were no blobs he told me, which is why it was tethered), and so naively I had tried restoring the device normally in iTunes since it was on a recovery screen and I had assumed it would go away with a restore, but the restore failed half way with a -1100 error when "verifying" the restore. I informed my friend to which they realized what I did, and even after sending my the files to try a tethered boot, it didn't work since I had already restored iOS 15 onto it. The phone has no data of any importance, but neither of us cannot get it into a functional state despite it working perfectly fine before what I had done. Did I mess up? Is the phone bricked?