Boot looping

You will need to plug it in to iTunes and attempt a update, and then attempt a restore from iTunes if the update doesn’t work. If both those are failing then the phone has something wrong with it hardware wise and it will need to be replaced, if you have apple care then take it to the apple store or talk to a online technician to get it replaced. If you don’t you will have to pay out of warranty cost for a whole new device. But definitely try the update and then try restore.