battery overheating on iPhone SE 2nd Gen

Last night, my phone began to get very hot, nearly too hot to touch and I could not get to the unlock page by pressing the Home Button. To avoid a fire, I wrapped it loosely in aluminum foil to keep it dry, and set it on two bricks on a big slate mini-patio outside the house. After 45 minutes or an hour, it was cold, but still unresponsive to any buttons whatever, including pressing the side button and the up-volume button together.

Does this sound like the battery was faulty? Or is there some problem with running too many apps?