The worst that could have happened is that putting the hot phone in the freezer could cause the
LCD screen to crack (due to going from very hot to very cold so quickly).
Extreme heat can ruin
LCD displays making them all black (a good reason never to leave anything with a
LCD in your car during the summer in most states).
Extreme or rapid temp changes can make an iffy soldered connection worse, especially connections where something is plugged in and out often, Wired headphones, data cables, chargers, etc.
Hopefully the phone is ok.