My dad basically gave me this scenario once.

Dad: My phone’s been kind of puffy recently, the back’s all blown out. Probably all the coolant at work corroding it. Still works alright though.

Me: Dad, that means the battery is super volatile and it could explode into flames at any moment. Get rid of it immediately.

Dad, rolling eyes: Well aren’t you just a little ray of sunshine?

I got him to replace the phone.