iPhone 12 Pro locked

I have put my IPhone 12 Pro on iTunes and it act like it is going to work and in about 5 minutes the phone will turn itself off and I have to restart all over again. What can I do because I don’t have my iPhone anymore because I forgot my passcode and I locked it up and I can’t seem to be able to get it to function properly on iTunes at all. What may be the problem. Can someone please help me? If so I will be grateful to you for taking the time to help me. I am hoping to hear from someone soon. Thank You for your help and time.

[Edited by Moderator]