iPhone 7 New and freezes can't shut down!!!

I have an iphone 7 thats 2 months old never dropped and never had water damage and just started having issues 1 week ago. If I was to restart or shut down phone and then restart, when it comes back up I get a ! mark next to messages icon and I can't load any apps at all their all blank when you open them. I talked to Apple they said to do a fresh Itunes restore NOT a Back Up. I did that and phone was working fine for 2 days and now starting to freeze but now on Apple Logo for 20 minutes then it shuts itself off and restarts then gets stuck again. I have to hold power button and volume down to "force restart" it at least 4-5 times before system back up and running. One failure Apple never built in is a "force shut down". It would be nice if your phone gets stuck you can shut it down so the display doesn't permanently stay on stuck and heats up your device and drains your battery. I'm taking the phone in on Saturday however what proof do I have that its having issues? They may say it works fine and our diagnostics don't see anything. I have recorded a video of the Apple Logo frozen but thats about it. My concern is IF they replace phone does Apple give you refurbished garbage because it would stink to lose a new phone? I don't know if this is a known issue of the IOS 11.3.1 or a hardware issue.